Add new command cargo why (as an alias for cargo tree --invert)

[KSXGitHub]

Problem

Sometimes the user wants to find out why a particular package is installed in my dependency tree. cargo tree --invert is precisely what they need but it's too obscure to figure out. It's also hard to type.

Proposed Solution

New command called cargo why

Notes

No response

[epage]

Closing as a duplicate of #10006. if you want us to consider re-opening it, let us know that and why it would be valuable to have this alias vs teaching people of existing commands.

Note: someone is working on #948 and some things we might consider is rendering the relevant trees or telling people of the commands to find more information.