feat: improving enhancer loading timing

[kptdobe]

Introduces a new capability: let the consumer define when to load the enhancer. To do so:

• set window.hlx.RUM_MANUAL_ENHANCE = true;
• initialize rum with sampleRUM();
• when ready - best solution, post LCP - call sampleRUM.enhance();

[github-actions[bot]]

This PR will trigger no release when merged.

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 100.00%. Comparing base (830fd72) to head (32fc673).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #175 +/- ## ========================================= Coverage 100.00% 100.00% ========================================= Files 1 1 Lines 66 69 +3 ========================================= + Hits 66 69 +3 ```

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[adobe-bot]

:tada: This PR is included in version 2.2.0 :tada:

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

Your semantic-release bot :package::rocket:

[trieloff]

This seems to be messing with https://github.com/adobe/helix-rum-enhancer/pull/256 need to understand why

[trieloff]

Faster loading of rum-enhancer in the default behavior means that the URL manipulation needed for the test is coming too late. Fixed in https://github.com/adobe/helix-rum-enhancer/pull/256/commits/bd2eae39df4784dfb85c0e4a8d166748837dffd5