Allow literal-only string parsing

[TPGamesNL]

Description

Allows for strings to be parsed as literals in script, e.g. when a pattern contains %*string%. Comment said this would be handled by VariableString, but this isn't the case when talking about literal parsing (VariableString isn't allowed in this case).

TODO: check behaviour with expression in it

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Target Minecraft Versions: any Requirements: none Related Issues: #4664

[Pikachu920]

this only allows simple variablestrings to be used as literals, right? also, what about a case where a variablestring is not simple but it only consists of literal text and literal expressions?

[TheLimeGlass]

This is going to be required for text displays in 1.19.4 parsing from the lang pattern of an entity data.