Add date, detekt-version + link to HtmlReport

[schalkms]

These tags are added to the appendix of the HtmlReport.

Closes #2416

[codecov-io]

Codecov Report

Merging #2470 into master will increase coverage by <.01%.
The diff coverage is 83.33%.

@@             Coverage Diff              @@
##             master    #2470      +/-   ##
============================================
+ Coverage     83.28%   83.29%   +<.01%     
- Complexity     2196     2198       +2     
============================================
  Files           360      360              
  Lines          6216     6231      +15     
  Branches       1141     1144       +3     
============================================
+ Hits           5177     5190      +13     
  Misses          463      463              
- Partials        576      578       +2

Impacted Files	Coverage Δ	Complexity Δ
...tlab/arturbosch/detekt/cli/out/HtmlOutputReport.kt	95.89% <83.33%> (-1.13%)	20 <2> (+2)
...rbosch/detekt/rules/complexity/ComplexInterface.kt	93.1% <0%> (-6.9%)	14% <0%> (-1%)
...lab/arturbosch/detekt/formatting/FormattingRule.kt	93.33% <0%> (-2.97%)	13% <0%> (ø)
...b/arturbosch/detekt/cli/baseline/BaselineFacade.kt	89.47% <0%> (-0.53%)	10% <0%> (ø)
.../io/gitlab/arturbosch/detekt/cli/runners/Runner.kt	94.11% <0%> (+1.8%)	11% <0%> (-1%)	⬇️
...b/arturbosch/detekt/api/internal/DetektPomModel.kt	70.58% <0%> (+1.83%)	5% <0%> (ø)	⬇️
.../arturbosch/detekt/cli/baseline/BaselineHandler.kt	77.77% <0%> (+5.55%)	14% <0%> (+2%)	⬆️

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