refactor(message-builder): move static helper methods to functions

[Nerixyz]

These functions shouldn't live in the message builder. They're related to IRC and Ignores.
IRC related functions are in TwitchIrc and in the chatterino::twitchirc namespace. All functions were copied. Only parameters equal to originalMessage were renamed to content to avoid confusion with the original message text, which might be bigger.

In the future, we should get rid of the ints in this code.

clang-tidy will complain, but I didn't change anything.

[github-actions]

clang-tidy made some suggestions

[github-actions]

clang-tidy made some suggestions

[pajlada]

parameters equal to originalMessage were renamed to content to avoid confusion with the original message text, which might be bigger.

I don't understand the reasoning behind the change - I don't really care too much about it, but I don't see how originalMessage would be incorrect

[Nerixyz]

but I don't see how originalMessage would be incorrect

It's not incorrect, but it's misleading. For the reply @user foo bar, the content could be foo bar. Yes, foo bar is originalMessage_ of MessageBuilder, but it's not the "original" message - that would be @user foo bar.

[github-actions]

clang-tidy made some suggestions

[pajlada]

but I don't see how originalMessage would be incorrect

It's not incorrect, but it's misleading. For the reply @user foo bar, the content could be foo bar. Yes, foo bar is originalMessage_ of MessageBuilder, but it's not the "original" message - that would be @user foo bar.

Sure, I guess that depends on how you interpret "message" and "content". Libcommuni interprets "content" as @user foo bar