[8.17](backport #7456) Support replace directives in otel readme mage command

[mergify]

What does this PR do?

Makes the otel:readme mage command support replace directives. It now also supports pseudo-versions that Go uses for commit hashes in go.mod.

The implementation now actually parses the go.mod file using x/mod.

Why is it important?

In order to resolve a dependency conflict between beats and otel 0.120.x, we're going to use our own fork of prometheusreceiver. See #7443 for this change made in the 8.18 branch.

Checklist

• 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

---

This is an automatic backport of pull request #7456 done by [Mergify](https://mergify.com).

[mergify]

Cherry-pick of 9071254 has failed:

On branch mergify/bp/8.17/pr-7456
Your branch is up to date with 'origin/8.17'.

You are currently cherry-picking commit 907125402.
  (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:
	new file:   dev-tools/mage/otel/deps.go
	new file:   dev-tools/mage/otel/deps_test.go
	modified:   magefile.go

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	both modified:   NOTICE.txt
	both modified:   go.mod

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)

[elasticmachine]

💔 Build Failed

• Buildkite Build
• Commit: 492b82c

Failed CI Steps

• Merge coverage reports
• :sonarqube: Continuous Code Inspection

History

• 💔 Build #19301 failed ab754b2

cc @swiatekm