Issue #3395954 by pdureau: Add new Legacy module for UI Patterns 1.x compatiiblity

modules/ui_patterns_legacy/src/ComponentConverter.php

modules/ui_patterns_legacy/src/ComponentDiscovery.php

modules/ui_patterns_legacy/src/ComponentWriter.php

...ns_legacy/src/Drush/Commands/UiPatternsLegacyCommands.php

modules/ui_patterns_legacy/src/Element/Pattern.php

...legacy/src/Plugin/Discovery/UIPatternsLegacyDiscovery.php

.../src/Plugin/Discovery/UiPatternsLegacyPluginDiscovery.php

modules/ui_patterns_legacy/src/PropConverter.php

modules/ui_patterns_legacy/src/RenderableConverter.php

modules/ui_patterns_legacy/src/Template/TwigExtension.php

modules/ui_patterns_legacy/src/UiPatternsLegacyManager.php

.../ui_patterns_legacy/src/UiPatternsLegacyPluginManager.php

modules/ui_patterns_legacy/ui_patterns_legacy.services.yml

src/Plugin/UiPatterns/PropType/ListPropType.php

src/Sdc/UiPatternsSdcPluginManager.php