Support "Show decoded TASTY" on TASTy files

[KacperFKorban]

Is your feature request related to a problem? Please describe.

It would be great to be able to read decoded tasty directly from TASTy files in addition to the current way of reading TASTy files associated with scala files. This would be very useful for any tooling-related work. This is useful for cases when we don't have a scala file and just want to read the TASTy.

Describe the solution you'd like

I would like to be able to right-click on a tasty file and display a prettified version of the file, exactly the same way as with scala files currently. ("Metals Analyse Source" > "Show decoded TASTy")

Describe alternatives you've considered

An alternative would be to make this the default action for displaying tasty files.

Additional context

I think that this should be fairly easy, since AFAIK the current "Show decoded TASTy" feature first finds the TASTy file and then prettifies it. So, the bulk of this feature should be already implemented.

Search terms

TASTy, analysis