Make app, group, and tag descriptions requirable

[barborico]

Overview of Changes

Descriptions are important for usability and auditability--let's let Access deployers make them required! This PR adds support for an environment variable REQUIRE_DESCRIPTIONS which, if set to True, will make descriptions required when creating/editing apps, groups, and tags.

Front end environment loading

I made another change (the second commit) to how Vite loads environment so that it will pull variables set in .env files, but will still use the process env as the final source of truth. This was necessary to be able to test the frontend conditional form field requirements locally (or other config-based behavior like the web app name).

Before: Only read from shell/system environment
Now: Read from both .env files AND shell environment, with shell taking precedence

Partial updates for apps, groups, and tags

To more consistently support Marshmallow's default loading without clearing properties omitted in a PUT request, I've updated the schema loading to apply partial updates.

Testing

With REQUIRE_DESCRIPTIONS=True:

With REQUIRE_DESCRIPTIONS=False or omitting the variable altogether, the original behavior is preserved.

[eguerrant]

If possible, please add tests for these changes

[eguerrant]

Feel free to leave as is but since the bool is being ingested as a string, would we want to be more flexible and allow things like 'true', 'True', 'TRUE' etc?