[9.1] (backport #9903) [EDOT] - add header setter extension

[mergify]

What does this PR do?

This PR adds headersettetextension to EDOT.

Why is it important?

This extension is pretty useful to set headers based on request context/based on the configurations and can be helpful to route requests to various backends. We recently got an issue for same.

• I have read and understood the pull request guidelines of this project.
• My code follows the style guidelines of this project
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have made corresponding change to the default configuration files
• I have added tests that prove my fix is effective or that my feature works
• I have added an entry in ./changelog/fragments using the changelog tool
• I have added an integration test or an E2E test

Disruptive User Impact

How to test this PR locally

1. Build elastic-agent from this branch.
2. Run the following config:

receivers:
  filelog:
    include: [ /var/log/system.log ]
    start_at: beginning
    storage: file_storage/filelogreceiver

exporters:
  debug:
    verbosity: detailed
    sampling_initial: 10000
    sampling_thereafter: 10000

extensions:
  headers_setter:
    headers:
    - action: upsert
      key: User-ID
      value: user_id

service:
  extensions: [headers_setter]
  pipelines:
    logs:
      receivers: [filelog]
      exporters:
        - debug

Related issues

• Closes Add OTel Collector Contrib headerssetterextension to EDOT #9889

---

This is an automatic backport of pull request #9903 done by [Mergify](https://mergify.com).

[mergify]

Cherry-pick of 593a8b9 has failed:

On branch mergify/bp/9.1/pr-9903
Your branch is up to date with 'origin/9.1'.

You are currently cherry-picking commit 593a8b905.
  (fix conflicts and run "git cherry-pick --continue")
  (use "git cherry-pick --skip" to skip this patch)
  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Changes to be committed:
	modified:   NOTICE-fips.txt
	modified:   NOTICE.txt
	new file:   changelog/fragments/1757668211-add-headersetter-extension-to-EDOT.yaml
	modified:   go.sum
	modified:   internal/pkg/otel/README.md
	modified:   internal/pkg/otel/testdata/all-components.yml

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	both modified:   go.mod
	both modified:   internal/pkg/otel/components.go

To fix up this pull request, you can check it out locally. See documentation: https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/checking-out-pull-requests-locally

[elasticmachine]

Pinging @elastic/elastic-agent-control-plane (Team:Elastic-Agent-Control-Plane)

[mergify]

This pull request has not been merged yet. Could you please review and merge it @VihasMakwana? 🙏

[mykola-elastic]

In the components.go the headersetterextension import is under "receivers" section, please move it to "extensions"

[elasticmachine]

⏳ Build in-progress, with failures

• Buildkite Build
• Commit: 5f45cab

Failed CI Steps

• check-ci

History

• 💔 Build #27155 failed 5a9fdd2

cc @VihasMakwana

[elastic-sonarqube]

Quality Gate passed

Issues
0 New issues
0 Fixed issues
0 Accepted issues

Measures
0 Security Hotspots
100.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube