feat: Added select/deselect all notes button

[Edgiest05]

Introduced button in recent page footer that allows for selection of all notes

When less than all files are selected

When all files have already been selected, behaviour changes to unselect all

While implementing this I had to address that newer version of the saver_gallery dependency would not compile.
Furthermore preview_card makes use of a different variable expanded when it actually should never differ from the widget.selected one (or else some selection changes do not reflect in the UI). I've kept it for consistency's sake.

[Edgiest05]

Same functionality is now available also in each directory of the browse page

[codecov]

Codecov Report

Attention: Patch coverage is 2.77778% with 35 lines in your changes missing coverage. Please review.

Project coverage is 45.92%. Comparing base (c873848) to head (163af17).

Files with missing lines	Patch %	Lines
lib/pages/home/browse.dart	0.00%	14 Missing ⚠️
lib/components/home/select_all_button.dart	0.00%	12 Missing ⚠️
lib/pages/home/recent_notes.dart	0.00%	9 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1377      +/-   ##
==========================================
- Coverage   46.09%   45.92%   -0.17%     
==========================================
  Files         117      118       +1     
  Lines        8683     8716      +33     
==========================================
+ Hits         4002     4003       +1     
- Misses       4681     4713      +32     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[Edgiest05]

Resolved merge conflicts and updated saver_gallery to new version.