feat(`foundryup`): add `version` field to `foundry.toml` ("engines" equivalent) that is selected upon running `foundryup --use`

[roninjin10]

Component

Forge

Describe the feature you would like

npm has an engines field that allows you to specify a specific engine such as pnpm, node > 18 ect.

Similarly it would be nice if in a foundry.toml we could specify that foundry has to be pinned to a specific version or higher than a specific version.

When running foundryup --use it looks at this version field and then activate the corresponding version, downloading if not available.

This would mirror the behavior of something like nvm use.

It is important that a user activates rather than switch automatically.

Additional notes

One area that may be challenging to implement this is the foundry-toolchain as it would need to be aware of the version field in foundry.toml to select the version to install.

[mds1]

@Evalir this seems like something that would be good to support once we have v1 and semver