environment-views: fix bug where missing recipe/repo breaks env commands (#17608)

* environment-views: fix bug where missing recipe/repo breaks env commands

When a recipe or a repo has been removed from Spack and an environment
is active, it causes the view activation to crash Spack before any
commands can be executed. Further, the error message it not at all clear
in explaining the issue.

This forces view regeneration to always start from scratch to avoid the
missing package recipes, and defaults add_view=False in main for views activated
by the `spack -e` option.

* add messages to env status and deactivate

Warn users that a view may be corrupt when deactivating an environment
or checking its status while active. Updated message for activate.

* tests for view checking

Co-authored-by: Gregory Becker <becker33@llnl.gov>