Move opentelemetry-collector-builder to core

[jpkrohling]

This PR brings the opentelemetry-collector-builder repository to the core.

This was done by taking the builder repository, moving all its contents to the "builder" directory, adding that repository as a remote to this, and performing a merge with unrelated histories (--allow-unrelated-histories). This should not be squashed, so that the history is kept.

Closes #4275

List of commits:
- Initial commit

• Add CODEOWNERS file (Create CODEOWNERS #2)
• Moved from github.com/observatorium/opentelemetry-collector-builder (Update CODEOWNERS #3)
• fixed panics (Add @songy23 as approver #6)
• Replace master with main in CI and mergify files (Introduce end-to-end performance test bed #8)
• Bump to OpenTelemetry Collector 0.20.0 (documentation: add some vision notes to clarify relationships with FluentBit and Prometheus #10)
• Explicitly enable Go modules in quickstart instructions (Identify receivers, exporters and processors that will be part of the core. #13)
• Update to collector v0.21.0 (WIP: Rename OpenCensus to OpenTelemetry #17)
• Update to collector v0.22.0 (Update initial docs to OpenTelemetry #19)
• Download go modules before building (Change census-instrumentation to open-telemetry and update authors #20)
• Add version command (Build receivers based on new configuration #25)
• Pass errors from cobra Execute back to main for correct exit code (make docker-otelsvc fails #28)
• Update to collector v0.23.0 ([IGNORE] Dummy change to trigger Travis CI build #27)
• Generate a warning if the builder and collector base version mismatch (Add resource for VM Metrics receiver. #30)
• Update to OpenTelemetry Collector 0.24.0
• Don't use %w formatting with log.Fatal (Add factory and new-style config for VMMetrics receiver #35)
• Update to OpenTelemetry Collector 0.25.0 (Add factory and new-style config for Jaeger exporter #36)
• Update to 0.26.0 and update BuildInfo (Add factory and new-style config for Zipkin exporter #39)
• Sync build and CI Go versions at latest 1.16 (Add factory and new-style config for Zipkin receiver  #34)
• Add option to generate go code only (no compile) (Add factory and new-style config for Zipkin receiver #40)
• Don't reuse exec.Cmd (Add factory and new-style config for Prometheus receiver #42)
• Update to OpenTelemetry Collector 0.27.0 (BUG: Data race in TestApplication_StartUnified #43)
• Add CI Badge (Add factory and new-style config for Queued processor #47)
• Update to Collector v0.28.0 (cmd/occollectpr/Dockerfile and cmd/otelsvc/Dockerfile assumes platform is always linux #49)
• Account for go mod download in go1.17 not updating go.sum (Remove docker-collector makefile target #50)
• Update to collector v0.29.0 (Add End-to-end test bed #54)
• Update to collector v0.30.0 (doc: update documentation for memory ballast usage #57)
• cmd: fix module flag default value to github.com/open-telemetry (test: mem ballast test fails on Darwin #58)
• Update to collector v0.31.0 (Import the changes in Prometheus receiver from OpenCensus-Service. #60)
• Update to v0.33.0 (Cache dependencies on Travis CI #62)
• Add excludes support to generated go.mod (testbed: validate perf and memory for ballast #63)
• Small cleanup for the builder files (Make perf testbed OS agnostic #64)
• Support building with Go 1.17 (Fix Preceiver creation in prometheusreceiver/factory.go to pass the logger #66)
• Update to OpenTelemetry core 0.34.0 (Enable E2E test running on Travis CI #68)
• Upgrade to OpenTelemetry Collector 0.35.0 (Improve handling of status code/message (#51) #70)
• Upgrade to OpenTelemetry Collector 0.36.0 (Add Memory Limiting Capability to Service #76)
• Generate custom service code for Windows (Update exporter creators to take a zap.Logger parameter #75)
• Remove Core from Module type (testbed: sometimes process is left running holding Jaeger UDP port 6831 #77)
• release 0.37.0 (Cleanup E2E tests #78)
• Move builder to subdirectory

[bogdandrutu]

I would prefer cmd/builder please

[jpkrohling]

I would prefer cmd/builder please

For the whole builder repository?

[bogdandrutu]

@jpkrohling yes was thinking for the whole. Let's just merge it anywhere then we can move.