Issues/3419186: Add hook_ENTITY_TYPE_form_mode_alter().

Closes #3419186

added 632 commits

• 14e319da...82d325ee - 630 commits from branch project:11.x
• 213bec07 - Merge branch '11.x' into 3419186-add-a-hookentitytypeformmodealter
• a3533745 - Added test for the hook

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