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 47.63%. Comparing base (c1c3059) to head (620a0dc).

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   47.80%   47.63%   -0.17%     
==========================================
  Files         115      116       +1     
  Lines        9094     9127      +33     
==========================================
+ Hits         4347     4348       +1     
- Misses       4747     4779      +32     

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[Edgiest05]

Resolved merge conflicts and updated saver_gallery to new version.