Make regClientScript and regClientHTMLBlock work in the manager

[halftrainedharry]

What does it do?

Adds scripts registered with regClientScript() or regClientHTMLBlock() to the output in the manager.

Why is it needed?

There is some inconsistency:
The modX class has the 4 functions regClientScript(), regClientHTMLBlock(), regClientStartupScript() and regClientStartupHTMLBlock().
On the frontend (outputting a resource) all 4 functions work.
In the manager, the functions regClientStartupScript() and regClientStartupHTMLBlock() work, but scripts registered with regClientScript() and regClientHTMLBlock() are ignored.

---

If there is a reason why these functions shouldn't work in the manager, then at least the MODX documentation (and the source code) should be updated to clearly state that this is the case.

How to test

• Create a plugin that uses the functions $modx->regClientScript() and $modx->regClientHTMLBlock() on a manager event (like e.g. OnManagerPageBeforeRender).
• Make sure the scripts get added to the HTML output.

Related issue(s)/PR(s)

Related discussion in the MODX forum: https://community.modx.com/t/13-years-and-6-months-regclientscript-still-not-working/8282

[codecov]

Codecov Report

Attention: Patch coverage is 60.00000% with 2 lines in your changes missing coverage. Please review.

Project coverage is 21.53%. Comparing base (b1a02c3) to head (704adab).
Report is 17 commits behind head on 3.x.

Files with missing lines	Patch %	Lines
core/src/Revolution/modManagerController.php	60.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff            @@
##                3.x   #16700   +/-   ##
=========================================
  Coverage     21.53%   21.53%           
  Complexity    10734    10734           
=========================================
  Files           565      565           
  Lines         32540    32547    +7     
=========================================
+ Hits           7007     7010    +3     
- Misses        25533    25537    +4     

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[modxcommunity]

This pull request has been mentioned on MODX Community. There might be relevant details there:

https://community.modx.com/t/13-years-and-6-months-regclientscript-still-not-working/8282/14