Include html Tag in FilterUrlEventArgs

[The-Nutty]

For our use case we would like to be able to selectively sanitize data URI's based on the tag they are in (allow in an img tag, disallow any where else).

So to enable this I have modified the FilterUrlEventArgs to include the html tag that the URL is being sanitized from allowing us to include this logic in the FilterUrl call back.

Any comments or other way of achieving our goal appreciated.

[codecov]

Codecov Report

Merging #286 (5994589) into master (918dba9) will increase coverage by 0.01%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #286      +/-   ##
==========================================
+ Coverage   93.40%   93.42%   +0.01%     
==========================================
  Files           4        4              
  Lines         682      684       +2     
  Branches       82       82              
==========================================
+ Hits          637      639       +2     
  Misses         34       34              
  Partials       11       11              

Impacted Files	Coverage Δ
src/HtmlSanitizer/EventArgs.cs	100.00% <100.00%> (ø)
src/HtmlSanitizer/HtmlSanitizer.cs	95.43% <100.00%> (ø)

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[mganss]

Thanks