Update UX of authentication methods' Group Mappings Widget (#28108)

...ise/auth/components/SettingsSAMLForm/SettingsSAMLForm.jsx

...h/components/SettingsSAMLForm/SettingsSAMLForm.styled.tsx

...tend/src/metabase/admin/people/components/GroupSelect.jsx

...admin/settings/components/widgets/GroupMappingsWidget.jsx

...dgets/GroupMappingsWidget/AddMappingRow/AddMappingRow.tsx

...nents/widgets/GroupMappingsWidget/AddMappingRow/index.tsx

...eleteGroupMappingModal/DeleteGroupMappingModal.styled.tsx

...idget/DeleteGroupMappingModal/DeleteGroupMappingModal.tsx

...teGroupMappingModal/DeleteGroupMappingModal.unit.spec.tsx

...ets/GroupMappingsWidget/DeleteGroupMappingModal/index.tsx

...nents/widgets/GroupMappingsWidget/GroupMappingsWidget.jsx

...idgets/GroupMappingsWidget/GroupMappingsWidget.styled.tsx

...ets/GroupMappingsWidget/GroupMappingsWidget.unit.spec.tsx

...s/widgets/GroupMappingsWidget/GroupSelect/GroupSelect.tsx

...ponents/widgets/GroupMappingsWidget/GroupSelect/index.tsx

...gets/GroupMappingsWidget/MappingRow/MappingRow.styled.tsx

...nts/widgets/GroupMappingsWidget/MappingRow/MappingRow.tsx

...mponents/widgets/GroupMappingsWidget/MappingRow/index.tsx

...settings/components/widgets/GroupMappingsWidget/index.tsx

.../settings/components/widgets/GroupMappingsWidget/types.ts