Adds LaTeX integrity check based on SnuggleTeX

[koppor]

This ports koppor#646 by @Zylence to here.

This refs #8712.

Background: Snuggletex

Snuggletex is a library from the University of Edinburgh for converting latex to XML, but can be used for latex parsing as well. It is extendible, easy to use and powerful, all whilst containing almost no external dependencies.
In the future, it could become our main latex parser for integrity checks.

What it does do

• ^
• _
• $
• commands: \command[opt]{arg}{...}
• verbs: \verb(*)...
• environments: \begin{env}[opt]{arg}{...}...\end{env}
• user-defined commands

What it does not do

• &
• \#
• %

Notes

Some commands may be missing, for example I found \text{} to be absent,
to check which commands are supported by default, refer here: CorePackageDefinitions.java
Thankfully, enough of the package is exposed to be able to inject new commands, like follows:
engine.getPackages().get(0).addComplexCommandOneArg("text", false, ALL_MODES,LR, StyleDeclarationInterpretation.NORMALSIZE, null, TextFlowContext.ALLOW_INLINE);

Not checked if this is the correct way to represent the text command, but now it parses it correctly.

Translation of SnuggleTeX error messages

We decided NOT to translate ALL SnuggleTeX error messagages. More than 30. See koppor/jabref@0966619 (#646) for the full list. I opted NOT to translate, because they are not used often (see koppor#646 (comment) for details)

Mandatory checks

• Change in CHANGELOG.md described in a way that is understandable for the average user (if applicable)
• Tests created for changes (if applicable)
• Manually tested changed features in running JabRef (always required)
• Screenshots added in PR description (for UI changes)
• Checked developer's documentation: Is the information available and up to date? If not, I outlined it in this pull request.
• Checked documentation: Is the information available and up to date? If not, I created an issue at https://github.com/JabRef/user-documentation/issues or, even better, I submitted a pull request to the documentation repository.

[github-actions]

The build for this PR is no longer available. Please visit https://builds.jabref.org/main/ for the latest build.

[Siedlerchr]

can you show a screenshot?

[koppor]

Screenshot:

BibTeX:

@Article{,
  journal = {$\left($},
  title   = {$x_i_j$},
}

[koppor]

Merge commit to preserve correct main author ship.

At squash-merge, GitHub would use my username and put @Zylence as "Co-Authored-By".