Add `spm outdated` command

[DecampsRenan]

Add a spm outdated command to list packages that have newer versions available.

spm (proposed)	npm	yarn	pnpm
spm outdated	npm outdated	yarn outdated	pnpm outdated

Expected behavior

$ spm outdated
Package    Current  Wanted  Latest
react      18.2.0   18.2.0  19.0.0
vite       5.0.0    5.0.12  6.1.0

The output format should match whatever the underlying package manager returns.