Admin Controller Freshen

[Spuds]

This is a run through the admin controllers to "freshen" the php level in a few areas.

• use static on closures that don't need $this
• arrow functions fn() => for some one line closures
• replace those \ElkArte\AdminController\XYZ calls with an import and XYZ::class
• some hardening
• some useless else removal
• early returns
• remove list()
• defer suggest.js
• cast ints in some of the queries
• positive logic in some if
• etc

[codecov[bot]]

Codecov Report

Attention: 507 lines in your changes are missing coverage. Please review.

Comparison is base (57d2e59) 33.72% compared to head (5f05d2c) 34.42%. Report is 1 commits behind head on development.

Files	Patch %	Lines
...rces/ElkArte/AdminController/ManageAttachments.php	11.94%	59 Missing :warning:
sources/ElkArte/AdminController/ManageFeatures.php	28.12%	46 Missing :warning:
sources/ElkArte/AdminController/ManageBans.php	0.00%	38 Missing :warning:
sources/ElkArte/AdminController/ManageMaillist.php	35.08%	37 Missing :warning:
...rces/ElkArte/AdminController/ManagePermissions.php	0.00%	33 Missing :warning:
sources/ElkArte/AdminController/ManageSmileys.php	0.00%	30 Missing :warning:
sources/ElkArte/AdminController/ManagePaid.php	6.45%	29 Missing :warning:
sources/ElkArte/AdminController/Maintenance.php	0.00%	25 Missing :warning:
sources/ElkArte/AdminController/ManageSearch.php	4.16%	23 Missing :warning:
sources/ElkArte/AdminController/ManageBoards.php	4.76%	20 Missing :warning:
... and 38 more

Additional details and impacted files

```diff @@ Coverage Diff @@ ## development #3755 +/- ## ================================================= + Coverage 33.72% 34.42% +0.69% + Complexity 16632 16583 -49 ================================================= Files 434 434 Lines 84034 83942 -92 ================================================= + Hits 28344 28895 +551 + Misses 55690 55047 -643 ```

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