Stdlib functions update

[wildum]

PR Description

This PR refers to the first two points of this issue: https://github.com/grafana/alloy/issues/1315

The stdlib is modified according to the accepted proposal: https://github.com/grafana/alloy/pull/1161

Old stdlib names are still valid but using them will result in a warning in the logs.

Name conflicts between custom components and stdlib functions will result in the custom components shadowing the stdlib functions and a warning in the logs.

Notes to the Reviewer

The PR is big because of all the refs to the stdlib.

I recommend reviewing commit by commit instead of the full diff.

The commits to update the refs contain only search and replace changes.

PR Checklist

• [x] CHANGELOG.md updated
• [x] Documentation added
• [x] Tests updated
• [x] Config converters updated