Add Filesystem API to jars

[Arthurm1]

Linked to scalameta/metals#3750
and scalameta/metals-languageclient#461

[Arthurm1]

@kpodsiad Do you know how do fix the ESLint errors here? I'm trying to implement an interface method but I don't need the parameters - hence they're unused. I thought prefixing with _ caused the errors to be ignored but that only works with local compilation, not the github actions ESLint stage.

I've copied Microsoft's example method from here

[kpodsiad]

@Arthurm1 you try different options that disable ESLint errors for unused params - https://eslint.org/docs/rules/no-unused-vars#varsignorepattern. varsIgnorePattern might be a could candidate - I used this to suppress errors for _ here

[Arthurm1]

@kpodsiad That works thanks!