poc: Enable volta uninstall [email protected]

[morishin]

This pull request is for a PoC.

As per #327, the volta uninstall command does not allow you to uninstall node or yarn.
However, I have many patch versions of node installed on my machine, and I wanted to delete older versions to free up unnecessary disk space.
Therefore, it is inconvenient that volta uninstall [email protected] is not possible.

I looked through the issues and Discord but couldn't understand why this has not been implemented for so many years, so I created a simple implementation for discussion.
I would like to know whether this approach is acceptable or if there are any concerns.

(The core of the implementation is here. The rest of the changes are not significant.)

fn uninstall(self: Box<Self>, _session: &mut Session) -> Fallible<()> {
    let home = volta_home()?;
    // Acquire a lock on the Volta directory, if possible, to prevent concurrent changes
    let _lock: Result<VoltaLock, crate::error::VoltaError> = VoltaLock::acquire();

    let node_dir = home.node_image_root_dir().join(self.version.to_string());
    if node_dir.exists() {
        remove_dir_if_exists(&node_dir)?;
        info!("{} 'node@{}' uninstalled", success_prefix(), self.version);
    } else {
        warn!("No version 'node@{}' found to uninstall", self.version);
    }

    Ok(())
}

[morishin]

This uninstall is a function of Spec. ↓

volta/crates/volta-core/src/tool/mod.rs

Lines 120 to 124 in 1776387

	/// Uninstall a tool, removing it from the local inventory
	///
	/// This is implemented on Spec, instead of Resolved, because there is currently no need to
	/// resolve the specific version before uninstalling a tool.
	pub fn uninstall(self) -> Fallible<()> {

What I want to do now is to perform an uninstall with a specified version like volta uninstall [email protected], so Spec::uninstall is not appropriate. Therefore, I considered defining Tool::uninstall. (Since Tool is the return type of Spec::resolve, I believe that "Resolved" mentioned in this comment refers to Tool).

But I'm not sure that I can replace Spec::uninstall with the Tool::uninstall completely.