Add support for RendezVous tests

[friedger]

Is your feature request related to a problem? Please describe.
As a developer, I want to write RendezVous tests. However, the type checker does not work in the .tests files used for rv.

Describe the solution you'd like
I can edit the tests files and see errors in Visual Studio Code

Describe alternatives you've considered
Develop tests and invariants in the main contract and move them out before committing.

Additional context
Fortifying catamaranswaps for sbtc with rv: friedger/clarity-catamaranswaps#6

[moodmosaic]

@hugocaillard, do you need any rendezvous/rv-related info from @BowTiedRadone or myself? Let us know, and we’ll add it here.
stacks-network/rendezvous

[hugocaillard]

Ah thanks for opening this.
I told @moodmosaic and @BowTiedRadone that I would open a generic issue for tests written in Clarity. Basically, natively and transparently handling .test.clar files (that wouldn't be deployed obviously). This won't be specifically for rendezvous, but it'll help.

I didn't open it yet, will do. (Once we have it, there'll be some work in rendezvous to handle it, but mostly removing custom and complex deployment logic.)

This probably won't happen before end Q1 or Q2