Issue #3454615: [2.0.0-alpha3] Improved source plugins organization

...rc/Plugin/Derivative/FieldPropertiesSourceDeriverBase.php

...rs/src/Plugin/Field/FieldFormatter/ComponentFormatter.php

...rc/Plugin/Field/FieldFormatter/ComponentFormatterBase.php

...Plugin/Field/FieldFormatter/ComponentPerItemFormatter.php

...matters/src/Plugin/UiPatterns/Source/FieldLabelSource.php

...erns_field_formatters/ui_patterns_field_formatters.module

...ns_views/src/Plugin/UiPatterns/Source/ViewFieldSource.php

...ews/src/Plugin/UiPatterns/Source/ViewGroupTitleSource.php

...rns_views/src/Plugin/UiPatterns/Source/ViewRowsSource.php

...ns_views/src/Plugin/UiPatterns/Source/ViewsSourceBase.php

...ews/src/Plugin/UiPatterns/Source/ViewsStyleSourceBase.php

..._patterns_views/src/Plugin/views/style/ComponentStyle.php

modules/ui_patterns_views/src/UiPatternsViewsManager.php

src/Annotation/Source.php

src/Plugin/Context/RequirementsContext.php

src/Plugin/Context/RequirementsContextDefinition.php

...n/Validation/Constraint/RequiredArrayValuesConstraint.php

...ion/Constraint/RequiredArrayValuesConstraintValidator.php

src/SourcePluginBase.php

src/SourcePluginManager.php