Add DirectiveTestBed

[remscodes]

• Rework RenderedTestBed.
• Add DirectiveTestBed.

[codecov]

Codecov Report

Attention: 1 lines in your changes are missing coverage. Please review.

Comparison is base (360a2d0) 98.26% compared to head (11fa4c5) 98.17%.

Files	Patch %	Lines
...b/directive-test-bed/directive-test-bed-factory.ts	88.88%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #71      +/-   ##
==========================================
- Coverage   98.26%   98.17%   -0.09%     
==========================================
  Files          73       80       +7     
  Lines         345      383      +38     
  Branches       71       77       +6     
==========================================
+ Hits          339      376      +37     
- Misses          6        7       +1     

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