extracted tag parsing logic, changes for NET6/NET7

[AoshiW]

Changes:

• (performance) changes for NET6/NET7/netstandard2.1
• deleted all Color Color properties (or replaced by string HexColor property) and created interface for easier parsing of HexColor on user-side
• replace all string TmiSendTs properties with DateTimeOffset TmiSend
• extracted tag parsing logic into a separate class

[Syzuna]

I don't quite get why you changed it first just to revert it for a nicer gitdiff?

[AoshiW]

I changed it to tag.Value automatically without thinking but then I realized that it was an unnecessary change (and maybe even unwanted) so I changed it back to
(so please use Squash and merge so no one sees my useless commits)

[neon-sunset]

@AoshiW Btw, if you want to clean up git history, you can "Undo" commits in VS Code + GitLens or just reset to a, let's say, previous commit, then commit again in the desired form, and then git push -f - this will override commit history, making it look as if the previous commits never happened. People do this in popular and/or big repositories a lot.

[swiftyspiffy]

lgtm, just seeking clarity on the Color possible issue

[swiftyspiffy]

lgtm