[FIX] Return token in Lezer parser only when it applies

[jpelay]

Description

On Spanish, Bulgarian, and possibly other languages, there was an error when highlighting for commands, because in these languages the word for in and at is the same. This PR fixes that and also fixes it in other possible occurrences of the same problem by only returning the token if the parser can shift the state were the token be accepted, for example take into consideration the following code of level 10:

para animal en animales
    imprimir animal

The English version of this program is:

for animal in animales
    print animal

When the parser reaches the token en, the stack already has: [For, Text]. Then it iterates through every keyword relevant for this level in the highlighting.json dictionary and asks: Does en matches the regex for the current keyword? If it does, it then asks, can the parser shifts if I accept this token? If the answer is yes, it is accepted, if it ins't it continues to the next token, and finishes when it finds one that it can accept or it returns -1, in the case than none is accepted.

The problem was in this last step: we didn't ask if the parser would be in a good state if we accepted the token, resulting in accepting the first token that was found.

Fixes #4772

How to test

Go to level 12, set the language to Spanish and write:

para nombre en nombres
    imprimir nombre ' pertenece a ' casas en aleatorio
    imprimir nombre ' es mejor en ' asignaturas en aleatorio
    imprimir nombre ' su gran miedo es ' miedos en aleatorio

[jpelay]

This break nested ifs :(

[jpelay]

I think for this to move forward I need to fix the grammar a bit, and handle indentation properly.

[jpelay]

@Felienne This PR is ready now! I also added some tests for levels 5, 6 and 7, please take a look whenever you want

[Felienne]

Works!

[mergify]

Thank you for contributing! Your pull request is now going on the merge train (choo choo! Do not click update from main anymore, and be sure to allow changes to be pushed to your fork).

[mergify]

Thank you for contributing! Your pull request is now going on the merge train (choo choo! Do not click update from main anymore, and be sure to allow changes to be pushed to your fork).