Overhaul action states and add icons to toolbar

[droidmonkey]

• Fixes Going to application settings and back to entry view disables several context menu items #10981

Screenshots

Testing strategy

Added unit tests and tested extensively manually

Type of change

• ✅ Bug fix (non-breaking change that fixes an issue)
• ✅ New feature (change that adds functionality)

[varjolintu]

Something I noticed while debugging:
https://github.com/keepassxreboot/keepassxc/blob/develop/src/gui/EntryPreviewWidget.cpp#L544 This is constantly updated even if the config setting has disabled showing the TOTP in the Preview Panel.

EDIT: Maybe the whole Preview Panel shouldn't get updated if it's not even visible.

[michaelk83]

Consider grouping the new Database Settings toolbar icon into the existing Settings icon, with a dropdown. And in that case, you can remove the separator between the Passkeys and Password Generator, since these icons can be considered as just four tools: passkeys, reports, generator, settings.

[codecov]

Codecov Report

Attention: Patch coverage is 94.28571% with 10 lines in your changes missing coverage. Please review.

Project coverage is 63.36%. Comparing base (c8fc25e) to head (e591dbc).
Report is 1 commits behind head on develop.

Files with missing lines	Patch %	Lines
src/gui/reports/ReportsDialog.cpp	0.00%	6 Missing ⚠️
src/gui/DatabaseTabWidget.cpp	77.78%	2 Missing ⚠️
src/fdosecrets/objects/Service.cpp	0.00%	1 Missing ⚠️
src/gui/DatabaseWidget.cpp	96.43%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           develop   #11047      +/-   ##
===========================================
+ Coverage    62.97%   63.36%   +0.39%     
===========================================
  Files          362      362              
  Lines        37783    37729      -54     
===========================================
+ Hits         23793    23906     +113     
+ Misses       13990    13823     -167     

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[droidmonkey]

@phoerious this is ready for review