feat: add partial toolchain support from CLI

[lima-limon-inc]

Currently, installing partial toolchains is limited to the miden-toolchain.toml file for a specific directory.

This functionality could be re-surfaced in other areas of midenup.

@plafer suggested that the installation process could be interactive (i.e. prompts for verification before installing each component).

I believe the feature would mean an improvement in UX, however, maybe it could be limited to cases where miden auto installs toolchains instead of always prompting for confirmation; keeping midenup install stable the same.

[bitwalker]

I've recently added toolchain profiles (with a default minimal profile consisting of all non-optional components, and a full complete profile that installs everything). That provides the primary benefit of partial toolchains. When #184 is merged, we'll essentially support ad-hoc profiles (i.e. you pick a base profile, and then modify it).

We may want to add one or two more named profiles with more tailored sets of components for specific tasks - but to make that workable, we'll want to add a new key to the manifest that specifies the named profiles that each component gets installed under (other than complete, which always installs everything).