gir: Promisify class members in typescript generator

[ewlsh]

First stab at fixing promisifying...

gi.ts exposes a function called promisifyFunctions which handles creating promisified versions of functions based on their signature. Eventually this should instead use the async annotations GLib is working to support.

Needs testing to ensure output is correct

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@ewlsh looks like there are new conflicts (see failed action), how are you handling conflicts so far?

A simple additional test could be to add another example that uses one of the async methods from the issue that did not work before. The GitHub action also validates the types of the examples

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@ewlsh I have split ModuleGenerator, NpmPackage and TypeDefinitionGenerator into seperate files, this is the reason why you have a merge conflict. Do you want to fix it yourself or should I do it?