Fix EffReplace escaping characters when not needed

[TPGamesNL]

Description

Update EffReplace and StringUtils so it only escapes the replacement string if needed, which is only if the replacement is done with regex, which is only done if case sensitivity is disabled.

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Target Minecraft Versions: any
Requirements: none
Related Issues: #1226

[APickledWalrus]

Looks good to me. Wouldn't this only happen if case sensitivity is disabled though, or am I missing something? Also, does this change need done for the replaceFirst method too (it uses regex too iirc)?

[TPGamesNL]

Oh yea I mistyped that, my bad. StringUtils.replaceFirst doesn't need this, since both of those are regex, not just the non-case sensitive one, and EffReplace does the escaping already.