Support more complex add dep configuration, e.g. `:only`

[zachallaun]

Is your feature request related to a problem? Please describe.
I was playing around with building an Igniter installer for a library of mine, but found that the high-level Project.Deps utils do not support adding deps with more complex configuration, e.g. {:mneme, ">= 0.0.0", only: :test}

Describe the solution you'd like
Instead of accepting the package name and version as separate arguments, I'd propose that a dep tuple be passed in and inserted or used to replace existing dep tuples based on a matching first argument.

Describe alternatives you've considered
Unless I'm mistaken, the only alternative at the moment is to use much lower-level tools to modify the deps list yourself.

[zachallaun]

You're a beast

[zachdaniel]

🙇 😆