[relay-compiler] Support for directives on fragment spreads for @inline fragments

## relay-compiler v 14.x.x feature request:

We are blocked from upgrading from version 12.x.x to the new compiler due to missing support for directives on inline fragment spreads. This is the error thrown by the new compiler:
`Directives on fragment spreads for @inline fragments are not yet supported`

Since v14 is the second major version upgrade without this feature support, I'm wondering if this is in the horizon or should we plan for refactoring this feature out of the codebase.

Thanks team.