feat: add experimental otelcol sidecar

[swiatekm]

Add the build infrastructure for a sidecar using Otelcol. This isn't used anywhere yet, and only allows the sidecar to be built locally. We use otelcolbuilder and goreleaser, plus a Makefile to manage them.

[kasia-kujawa]

Problem with building on mac

% make build
  • starting release...
  • loading                                          path=.goreleaser.yaml
  • skipping announce, publish and validate...
  • loading environment variables
  • getting and validating git state
    • git state                                      commit=074ad4d9c4cd455ebd4351afae513520d78726fa branch=feat/otelcol-sidecar current_tag=v0.9.0 previous_tag=v0.8.0 dirty=false
    • pipe skipped                                   reason=disabled during snapshot mode
    • took: 1s
  • parsing tag
  • setting defaults
    • pipe skipped                                   reason=release is disabled
  • snapshotting
    • building snapshot...                           version=0.9.0-SNAPSHOT-074ad4d
  • running before hooks
    • running                                        hook=make generate-sources VERSION={{ .Version }}
    • took: 18s
  • checking distribution directory
  • loading go mod information
    • pipe skipped                                   reason=not a go module
  • build prerequisites
  • writing effective config file
    • writing                                        config=dist/config.yaml
  • building binaries
    • building                                       binary=dist/otelcol-sidecar_linux_arm64/otelcol-sidecar
    • building                                       binary=dist/otelcol-sidecar_linux_amd64_v1/otelcol-sidecar
  ⨯ release failed after 19s                 error=failed to build for linux_arm64: exit status 1: go: cannot find main module, but found .git/config in /Users/kkujawa/git/tailing-sidecar/changed/tailing-sidecar
        to create a module there, run:
        cd ../.. && go mod init

make: *** [build] Error 1