Create UI: create new FF to enable filings per entity types

Currently there is a flag, `supported-filings`, that controls whether a filing is enabled (in Dev/Test/Prod). (Eg, IA, dissolution, registration and restoration.)

Instead, we should have a flag for each filing that controls which entities are allowed.

See #15734 for more details.

- [ ] create new dissolution flag in LD - see `supported-dissolution-entities`
- [ ] create new registration flag in LD
- [ ] create new restoration flag in LD
- [ ] delete current flag in code (and its usage)
- [ ] create new flags in code (with usages)
- [ ] archive (delete) the old flag in LD (add this to release ticket)

Start with issue #15734 and trace the existing `supported-filings` flag and its usages in the JavaScript code. Verify the dissolution, registration, and restoration entity flags in LD, then confirm each filing uses its corresponding flag and the old flag is removed and scheduled for archival.

Written by the indexing model from the issue text.