Replaced some sync methods for their async version

[gndelia]

See #265

I removed most of the sync functions, there are some scenarios which I am unsure what to do. For instance, those sync calls that are at module level (like src/index.ts line 50 or line 60)

Same for src/errors/transformErrorMessages.ts - I am unsure if I can make that function async

Still pending one change from getProjectPath() in src/index.ts

[gndelia]

There are some options I was unable to migrate - I think it's not possible. Like the following https://github.com/jaredpalmer/tsdx/blob/master/src/index.ts#L50 and a couple more that are code part of a module and therefore can't be async (that's my understanding)

[swyxio]

mm i think we had some merge conflicts from other PRs. if you have time to address them, be my guest, if not i'll try to update when i free up

[gndelia]

@sw-yx I rebased and solve the conflicts :)

[swyxio]

Thank you!

[agilgur5]

@all-contributors please add @gndelia for code

[allcontributors]

@agilgur5

I've put up a pull request to add @gndelia! 🎉