Memory and rendering improvements

[ScrubN]

• Use spans in SubstringToTextWidth and GetShapedTextPath
• Allow reusing a single shaper object when measuring text
• Get font reference in GetShapedTextPath instead of cloning the font
• Short circuit SubstringToTextWidth to a faster Skia method when the message does not contain delimiters or RTL
• Don't hide the renderoptions in GetFallbackFont
• Add more debug attributes
• Implement IDisposable on ChatRenderer, TwichEmote, ChatBadge, and CheerEmote to properly dispose of unmanaged resources instead of having to call GC.WaitForPendingFinalizers
• Rename HighlightMessage -> HighlightIcons and make it a private field of ChatRenderer
• Cache TwitchEmote codec values instead of repeatedly making the same extern calls
• Less copying and repeated accessing when resizing badges
• Return reference icon bitmaps instead of copied bitmaps to reduce redundant copying and disposing.
• Cleanup FFmpegProcess class
• Short circuit RemoveRestrictedComments when there are no restrictions
• Do less allocations in RemoveRestrictedComments
• Make string.ToLower() calls into string.Equals(..., StringComparison.OrdinalIgnoreCase)
• Use StringBuilder.Replace instead of string.Replace when generating ffmpeg args
• Do not uselessly render every previous comment when a render is starting at comment index 101 or later
• Refactor HighlightIcons to use spans to allocate no strings on average and do less redundant checks
• Add success check to TwitchEmote image decoding to throw an exception with a more descriptive message
• Only report render progress every 3 ticks for less object creations
• Replace concatenating formatted ToString's with a single formatted interpolated string
• Cache the SKImageInfo for each sectionImage for less extern calls
• Refactor bit prefix checking to do less allocations
• Reduce allocations made by TimeSpanHFormat.Format
• Reduce allocations made by the text chat serializer regarding timestamp formatting
• Move GetShapedTextPath to SKPaintExtensions and cache SKPaint.GetFont reflection
• Use a StringBuilder instead of concatenation when compiling message bodies
• Make banned word regexes local to the relevant function instead of a private field
• Fix ChatRender timestamps resetting after 24 hours
• Make ChatRender timestamps almost free
• Make gift-illus.png (highlight icon) fetching obey offline status
• Make bitmaps immutable and use SKImage over SKBitmap for icons
  • Apparently these increase performance when calling SKCanvas.DrawBitmap/SKCanvas.DrawImage by sharing memory handles instead of copying
• Fix HTML chat message timestamps resetting after 24 hours
• Reduce memory allocated by the HTML chat serializer
• Misc cleanup

[ScrubN]

I don't know why I didn't try spans before using the StringPool, but the difference in performance is insane. The renderer is still bottlenecked by copying to ffmpeg though :(

[ScrubN]

I need to stop making 1.5k line change PRs