Fix panic in D208 with multibyte indent (#9147)

Fix #9080

Example, where `[]` is a 2 byte non-breaking space:
```
def f():
    """ Docstring header
^^^^ Real indentation is 4 chars
      docstring body, over-indented
^^^^^^ Over-indentation is 6 - 4 = 2 chars due to this line
   [] []  docstring body 2, further indented
^^^^^ We take these 4 chars/5 bytes to match the docstring ...
     ^^^ ... and these 2 chars/3 bytes to remove the `over_indented_size` ...
        ^^ ... but preserve this real indent
```

crates/ruff_linter/resources/test/fixtures/pydocstyle/D.py

@@ -713,5 +713,12 @@ def retain_extra_whitespace_not_overindented():
 
     This is not overindented
         This is overindented, but since one line is not overindented this should not raise
-            And so is this, but it we should preserve the extra space on this line relative 
+            And so is this, but it we should preserve the extra space on this line relative
+    """
+
+
+def inconsistent_indent_byte_size():
+    """There's a non-breaking space (2-bytes) after 3 spaces (https://github.com/astral-sh/ruff/issues/9080).
+
+       Returns:
     """

crates/ruff_linter/src/rules/pydocstyle/rules/indent.rs

@@ -254,14 +254,26 @@ pub(crate) fn indent(checker: &mut Checker, docstring: &Docstring) {
                     Edit::range_deletion(TextRange::at(line.start(), line_indent.text_len()))
                 } else {
                     // Convert the character count to an offset within the source.
+                    // Example, where `[]` is a 2 byte non-breaking space:
+                    // ```
+                    // def f():
+                    //     """ Docstring header
+                    // ^^^^ Real indentation is 4 chars
+                    //       docstring body, over-indented
+                    // ^^^^^^ Over-indentation is 6 - 4 = 2 chars due to this line
+                    //    [] []  docstring body 2, further indented
+                    // ^^^^^ We take these 4 chars/5 bytes to match the docstring ...
+                    //      ^^^ ... and these 2 chars/3 bytes to remove the `over_indented_size` ...
+                    //         ^^ ... but preserve this real indent
+                    // ```
                     let offset = checker
                         .locator()
-                        .after(line.start() + indent.text_len())
+                        .after(line.start())
                         .chars()
-                        .take(over_indented_size)
+                        .take(docstring.indentation.chars().count() + over_indented_size)
                         .map(TextLen::text_len)
                         .sum::<TextSize>();
-                    let range = TextRange::at(line.start(), indent.text_len() + offset);
+                    let range = TextRange::at(line.start(), offset);
                     Edit::range_replacement(indent, range)
                 };
                 diagnostic.set_fix(Fix::safe_edit(edit));

crates/ruff_linter/src/rules/pydocstyle/snapshots/ruff_linter__rules__pydocstyle__tests__D208_D.py.snap

@@ -411,4 +411,22 @@ D.py:707:1: D208 [*] Docstring is over-indented
 709 709 | 
 710 710 | 
 
+D.py:723:1: D208 [*] Docstring is over-indented
+    |
+721 |     """There's a non-breaking space (2-bytes) after 3 spaces (https://github.com/astral-sh/ruff/issues/9080).
+722 | 
+723 |        Returns:
+    |  D208
+724 |     """
+    |
+    = help: Remove over-indentation
+
+ℹ Safe fix
+720 720 | def inconsistent_indent_byte_size():
+721 721 |     """There's a non-breaking space (2-bytes) after 3 spaces (https://github.com/astral-sh/ruff/issues/9080).
+722 722 | 
+723     |-       Returns:
+    723 |+    Returns:
+724 724 |     """
+
 

crates/ruff_linter/src/rules/pydocstyle/snapshots/ruff_linter__rules__pydocstyle__tests__D213_D.py.snap

@@ -662,7 +662,7 @@ D.py:712:5: D213 [*] Multi-line docstring summary should start at the second lin
 713 | | 
 714 | |     This is not overindented
 715 | |         This is overindented, but since one line is not overindented this should not raise
-716 | |             And so is this, but it we should preserve the extra space on this line relative 
+716 | |             And so is this, but it we should preserve the extra space on this line relative
 717 | |     """
     | |_______^ D213
     |
@@ -679,4 +679,27 @@ D.py:712:5: D213 [*] Multi-line docstring summary should start at the second lin
 714 715 |     This is not overindented
 715 716 |         This is overindented, but since one line is not overindented this should not raise
 
+D.py:721:5: D213 [*] Multi-line docstring summary should start at the second line
+    |
+720 |   def inconsistent_indent_byte_size():
+721 |       """There's a non-breaking space (2-bytes) after 3 spaces (https://github.com/astral-sh/ruff/issues/9080).
+    |  _____^
+722 | | 
+723 | |        Returns:
+724 | |     """
+    | |_______^ D213
+    |
+    = help: Insert line break and indentation after opening quotes
+
+ℹ Safe fix
+718 718 | 
+719 719 | 
+720 720 | def inconsistent_indent_byte_size():
+721     |-    """There's a non-breaking space (2-bytes) after 3 spaces (https://github.com/astral-sh/ruff/issues/9080).
+    721 |+    """
+    722 |+    There's a non-breaking space (2-bytes) after 3 spaces (https://github.com/astral-sh/ruff/issues/9080).
+722 723 | 
+723 724 |        Returns:
+724 725 |     """
+