Revert "Remove alpha-stability "workspace" module again."

core/composer.json

...l/core.entity_form_display.workspace.workspace.deploy.yml

...config/install/core.entity_form_mode.workspace.deploy.yml

core/modules/workspace/css/workspace.overview.css

core/modules/workspace/css/workspace.toolbar.css

core/modules/workspace/icons/000000/workspace.svg

core/modules/workspace/icons/81c071/ws_icon.svg

core/modules/workspace/icons/f0a100/ws_icon.svg

core/modules/workspace/src/Entity/Workspace.php

core/modules/workspace/src/Entity/WorkspaceAssociation.php

core/modules/workspace/src/EntityAccess.php

core/modules/workspace/src/EntityOperations.php

core/modules/workspace/src/EntityQuery/PgsqlQueryFactory.php

core/modules/workspace/src/EntityQuery/Query.php

core/modules/workspace/src/EntityQuery/QueryAggregate.php

core/modules/workspace/src/EntityQuery/QueryFactory.php

core/modules/workspace/src/EntityQuery/QueryTrait.php

core/modules/workspace/src/EntityQuery/Tables.php

core/modules/workspace/src/EntityTypeInfo.php

core/modules/workspace/src/Form/WorkspaceActivateForm.php