Use `not-installed` instead of `"not installed"` for `--status` filter values

[ernilambar]

Issue

The --status filter option in wp connectors list accepts not installed as a filter value. Standard WP-CLI commands do not use multi-word strings with spaces for CLI flag choices, as it forces users to quote arguments in the terminal (--status="not installed") and breaks standard CLI conventions.

Example

Command	Flag Example	Values Used
wp plugin list	--status=<status>	active, inactive, must-use, dropin, active-network
wp theme list	--status=<status>	active, inactive, parent
wp comment list	--status=<status>	hold, approve, spam, trash
wp post list	--post_status=<status>	publish, future, draft, pending, private, trash
wp language plugin list	--status=<status>	installed, uninstalled, active