Make relative paths in deps of bb.edn resolve relative to the bb.edn

[lispyclouds]

Is your feature request related to a problem? Please describe.
Currently, due to its nature of implementation in deps.clj and its use in bb, if relative paths via :local/root are used in the :deps of bb.edn, they are resolved relative to the pwd of the invocation and not the bb.edn.

Describe the solution you'd like
To make the expectation of all the paths in bb.edn resolve relative to it consistent the resolution of these paths should be changed as well.

Describe alternatives you've considered
None.

Additional context
Some points to consider:

• Since this is shelling out to the usual deps resolver, how does the classpath caching get affected by this change? Would it pollute the pwd now?

[borkdude]

The only change necessary to fix this is to use (:bb-deps-root ...) and bind the deps.clj *dir* variable to it (only if it's set, with-bindings allows you to do that conditionally.