feat(otel): add integrations components

[andrzej-stencel]

This is a "proof of concept" draft pull request, not to be merged.

It adds the following OTel Collector components, as implemented in elastic/opentelemetry-collector-components#96:

• config_integrations extension
• file_integrations extension
• integration receiver
• integration processor

I was able to build the agent binary using the command:

go build .

After that, I ran the agent in OTel mode with the following command:

./elastic-agent otel --config config.yaml

with the following config.yaml file:

exporters:
  debug:

extensions:
  config_integrations:
  file_integrations:
    path: .

processors:
  integration:
    name: integ2

receivers:
  integration:
    name: integ1

service:
  extensions:
    - config_integrations
    - file_integrations
  pipelines:
    logs:
      exporters:
        - debug
      processors:
        - integration
      receivers:
        - integration

[mergify]

This pull request does not have a backport label. Could you fix it @andrzej-stencel? 🙏
To fixup this pull request, you need to add the backport labels for the needed
branches, such as:

• backport-./d./d is the label to automatically backport to the 8./d branch. /d is the digit

[mergify]

backport-v8.x has been added to help with the transition to the new branch 8.x.
If you don't need it please use backport-skip label and remove the backport-8.x label.

[mergify]

This pull request does not have a backport label. Could you fix it @andrzej-stencel? 🙏
To fixup this pull request, you need to add the backport labels for the needed
branches, such as:

• backport-./d./d is the label to automatically backport to the 8./d branch. /d is the digit

[mergify]

backport-v8.x has been added to help with the transition to the new branch 8.x.
If you don't need it please use backport-skip label and remove the backport-8.x label.

[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

[mergify]

This pull request is now in conflicts. Could you fix it? 🙏
To fixup this pull request, you can check out it locally. See documentation: https://help.github.com/articles/checking-out-pull-requests-locally/

git fetch upstream
git checkout -b add-integrations-components upstream/add-integrations-components
git merge upstream/main
git push upstream add-integrations-components