Consider adding a `command` object to TerminalLink rather than the `handleTerminalLink` method

[eamodio]

Testing #101300

Again, this is mostly API ergonomics, but this would keep consistency with other APIs (CodeLens, StatusBarItems, TreeItems, etc). It also helps guide the usage of a command being required to return a link, and somewhat avoids calls to handleTerminalLink that take no action.

Additionally since the command object has a title property, that could be used in place of the tooltip property as well.

re: #101391 (comment)

/cc @jrieken

[Tyriar]

Decided not to do this #91290 (comment)