Refactor application settings

[samuelwei]

Fixes #985

Type (Highlight the corresponding type)

• Bugfix
• Feature
• Documentation
• Refactoring (e.g. Style updates, Test implementation, etc.)
• Other (please describe):

Checklist

• Code updated to current develop branch head
• Passes CI checks
• Is a part of an issue
• Tests added for the bugfix or newly implemented feature, describe below why if not
• Changelog is updated
• Documentation of code and features exists

Changes

• Drop old global application settings storage
• Add new global application settings storage
• Add database upgrade command for v2/v3 to v4
• Adjust docs
• Cleanup .env

Other information

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 95.83%. Comparing base (200cc55) to head (a789981).

Additional details and impacted files

@@              Coverage Diff              @@
##             develop     #989      +/-   ##
=============================================
+ Coverage      95.65%   95.83%   +0.17%     
- Complexity      1252     1288      +36     
=============================================
  Files            193      198       +5     
  Lines           4282     4413     +131     
=============================================
+ Hits            4096     4229     +133     
+ Misses           186      184       -2     

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[danimo]

As discussed, please consider fixing/adding Postgres compatibility by changing (introduced in 2022_09_27_193354_create_sessions_table.php):

-            $table->string('id')->index()->unique();
+            $table->string('id')->primary();

ideally this should be fixed in said migration, too.

[samuelwei]

As discussed, please consider fixing/adding Postgres compatibility by changing (introduced in 2022_09_27_193354_create_sessions_table.php):

-            $table->string('id')->index()->unique();
+            $table->string('id')->primary();

ideally this should be fixed in said migration, too.

These issues will be fixed first in #1079 and later adjusted to this PR

[danielmachill]

localisation, tests and upgrade documentation not yet reviewed

[danielmachill]

Review complete