Merge: lib: add `package.desc` keys to the `package.ini` file of most of the packages...

Merge: lib: add `package.desc` keys to the `package.ini` file of most of the packages in `lib`

This PR adds a `package.desc` key to all `package.ini` files into `lib/`.

For most of them the description is imported from the `mdoc_or_fallback.synopsis` with some light modifications (removing the starting `#` and the trailing `.`).

After this automated fix, 5 packages still missed the `package.desc` key:
* `dummy_array`
* `filter_stream`
* `graph`
* `mnit`
* `postgresql`

I manually added the key for `graph` and `postgresql`, so after this PR only 3 packages still miss the key:
* `dummy_array`
* `filter_stream`
* `mnit`

Pull-Request: #2667