fix: can change email to an existing email (resolves #1826)

[jobara]

Resolves #1826

• Updates the UniqueUserEmail custom rule to allow for specifying an id to ignore. Similar to how the unique laravel rule works.
• Uses the updated UniqueUserEmail rule in all places where emails are updated. Laravel's unique validation rule can't be used here because the e-mails are encrypted in the database.
• Note that tests weren't provided but I've filed a Write tests to validate user email update rules and behaviour #1833 writing them.

Prerequisites

If this PR changes PHP code or dependencies:

• I've run composer format and fixed any code formatting issues.
• I've run composer analyze and addressed any static analysis issues.
• I've run php artisan test and ensured that all tests pass.
• I've run composer localize to update localization source files and committed any changes.

If this PR changes CSS or JavaScript code or dependencies:

• I've run npm run lint and fixed any linting issues.
• I've run npm run build and ensured that CSS and JavaScript assets can be compiled.

[codecov]

Codecov Report

Merging #1834 (7bdb26e) into dev (6246a46) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@            Coverage Diff            @@
##                dev    #1834   +/-   ##
=========================================
  Coverage     96.52%   96.52%           
- Complexity     2032     2033    +1     
=========================================
  Files           301      301           
  Lines          8745     8755   +10     
=========================================
+ Hits           8441     8451   +10     
  Misses          304      304           

Impacted Files	Coverage Δ
...p/Actions/Fortify/UpdateUserProfileInformation.php	100.00% <100.00%> (ø)
app/Http/Controllers/IndividualController.php	100.00% <100.00%> (ø)
app/Http/Controllers/SettingsController.php	99.59% <100.00%> (ø)
...CommunicationAndConsultationPreferencesRequest.php	100.00% <100.00%> (ø)
...CommunicationAndConsultationPreferencesRequest.php	100.00% <100.00%> (ø)
app/Rules/UniqueUserEmail.php	100.00% <100.00%> (ø)