Style fixes

[snipe]

LOTS more work to go here, and some of the oh-insights errors (I think) we can ignore, but it's a lot to tackle at once.

[what-the-diff]

• Changed the isset() to null coalescing operator
• Added public keyword in front of const variables
• Removed curly braces from switch statements where they are not needed (PHP 7+)
• Replaced true === config('app.debug') with config('app.debug') === true for better readability and consistency
• Made show method in ModalController class public instead of private as it is called by other classes/methods outside this controller's scope
• Fix the email link in UserPresenter.php
• Add const DATA_SESSION_KEY = '_samlData' to Saml class
• Update composer dependencies and add phpinsights config file insights.php
• Remove unused routes from api route group (api/accessories, api/categories, etc)
• The variable $env_error_count was removed.
• In the if statement for APP_KEY, a curly brace was added to the string concatenation on line Make jquery data tables responsive #87 and another one in front of showline num on line 88.
• On lines 91-92, two variables were deleted: $appurl length = strlen($envvalue) and appurllength > 0). These are not used anywhere else in this file so they can be safely deleted without affecting anything else (I think?).
• A curly brace is missing from an echo statement at line 449 but I'm not sure what it's supposed to do because there isn't any code inside that block? It looks like maybe some debugging stuff or something? Not really sure why it would have been commented out though...

[snipe]

A curly brace is missing from an echo statement at line 449

A filename would be helpful here... 🤔

[snipe]

Love these additions, thank you @marcusmoore!