Done :
- add isUnique prop availability on gql update/create fieldMetadata
resolvers
- add unique index creation logic at update & creation
- add unique index deletion logic at update
- update unique index if field name updated
- edge cases : can't have default value and unique fields / standard
default value excluded from index (where clause) / can't have composite
unique fields / can't create unique fields on MORPH
closes https://github.com/twentyhq/core-team-issues/issues/1222