Fix update script screwing up scheduled report data (3.x)

Cannot use Exception as Exception because the name is already in use in core/Exception/PluginDeactivatedException.php on line 10

Do not issue warning/errors during update, when activating a plugin that is already activated (#10670)

move PluginDeactivatedException into Exception namespace

as a result of this change, we could (should?) remove the try/catch blocks around the activatePlugin calls in all Updates files

otherwise Piwik can be left in a state where a warning is displayed and it's hard to troubleshoot that config is only mentionned in config file

Merge 2.x => 3.x-dev

Website selector Icon is now in the right place refs https://github.com/piwik/piwik/pull/10646 https://github.com/piwik/piwik/issues/10641

Conflicts:
	plugins/ScheduledReports/javascripts/pdf.js
	plugins/ScheduledReports/templates/_addReport.twig

Clarify that we are in enforced LTS mode and will only merge code in 3.x

* fixes #10613 - show description as part of the datatable

Check if this fixes the issue. If not I'd likely move it out of 3.0

* updated our font pack, use some material design icons

* fix sign in icon, better help icon

* fix ui tests

* fix more screenshot tests

* add legal notice and readme

* fix remaining  tests

* Hide the new notification PHPVersionTooOldForNewestPiwikCheck in UI tests

* UI test minor update (one widget wasn't showing sparkline when it should)

* 2.16.3

2.16.3-rc3

 If Piwik is not installed yet, it's possible the tmp/ folder is not writable, display a useful error message