Add direct write save option

[droidmonkey]

• Closes Add a "Very Unsafe Save" option #6335 and closes Ability to disable explicit delete before overwriting the database file #1874
• Modify application settings presentation to allow for alternative saving strategies
• Transition Database::save calls to using flags to control saving behavior. Reduces boolean flags on function call.
• Made direct write save option a local setting to prevent unintentional carry over between platforms.

Also fixes infinite save bug when saving fails:

• Introduced in Properly block modified signal during Database destruction #6438, modified signal is not blocked at the Database level when emitting is blocked. This causes infinite saving to occur when Always Save After Every Change is enabled.

Screenshots

Testing strategy

Tested all three options (Atomic, Non-Atomic Temp File, and Non-Atomic Direct Write) on Windows and Linux
Tested against GVFS on Gnome 3

Type of change

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

[michaelk83]

@droidmonkey Would if help the gvfs situation if KPXC always used a local copy to open and save? IOW: copy to local disk → open from local disk → make changes → save to local disk → copy to origin? If this is what "Temporary file moved into place" does, I wonder why that still fails? Is the problem only when saving, or could there also be an issue when opening from gvfs?

A related idea is use a local temporary file but with atomic move. Database.cpp lines 348-353 are not atomic.
edit: Or is the problem with gvfs at the move operation?

[phoerious]

Ready to go, just one nitpick.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 73.91304% with 12 lines in your changes missing coverage. Please review.

Project coverage is 63.67%. Comparing base (bd744d1) to head (c153b22).
Report is 596 commits behind head on develop.

Files with missing lines	Patch %	Lines
src/core/Database.cpp	72.73%	6 Missing ⚠️
src/gui/DatabaseWidget.cpp	55.56%	4 Missing ⚠️
src/gui/ApplicationSettingsWidget.cpp	66.67%	2 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #6594      +/-   ##
===========================================
- Coverage    63.68%   63.67%   -0.01%     
===========================================
  Files          330      330              
  Lines        41601    41617      +16     
===========================================
+ Hits         26491    26496       +5     
- Misses       15110    15121      +11     

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