Move /submodules to /modules

👍 Thanks for doing this, @Utkarsh_33! Looks perfect 😊

Thanks to this MR being extracted, https://git.drupalcode.org/project/experience_builder/-/merge_requests/2... won't be changing *132* files anymore — 49 of those will have been handled here.

Going ahead and bypassing CODEOWNERS approval for this trivial change.

Because:

$ find . -type d -name "submodules"

→ 0 results!

$ find . -type d -name "modules"
./entity_embed/tests/modules
./json_field/modules
./json_field/modules/json_field_widget/tests/modules
./big_pipe_sessionless/tests/modules
./project_browser/tests/modules
./project_browser/modules
./search_api_solr/tests/modules
./search_api_solr/modules
./search_api_solr/modules/search_api_solr_legacy/tests/modules
./search_api/tests/modules
./search_api/modules
./migmag/tests/modules
./migmag/migmag_process/tests/modules
./config_split/tests/modules
./ckeditor5_premium_features/modules
./dynamic_entity_reference/tests/modules
./acquia_migrate/tests/modules
./component_library/modules

→ many results among the dozen or so contrib modules I happen to have installed.

Automatically closed - issue fixed for 2 weeks with no activity.