Fix bug determining required args of `returns table` functions

Description

Fixes #2216

returns table and out arguments count as arguments but not as input arguments (except inout args which count as both). Previously we calculated the number of required arguments as numberOfArguments - numberOfArgumentsWithDefaults; but this calculation should instead have been numberOfInputArguments - numberOfArgumentsWithDefaults - i.e. it only applies to input arguments. This is now resolved.

The result is that fewer arguments are now seen as required, making this a non-breaking change (though it may result in some arguments losing their non-null status, that is safe for existing queries).

Performance impact

Negligible.

Security impact

Doubtful.

Checklist

[x] My code matches the project's code style and yarn lint:fix passes.
[x] I've added tests for the new feature, and yarn test passes.
[ ] I have detailed the new feature in the relevant documentation.
[x] I have added this feature to 'Pending' in the RELEASE_NOTES.md file (if one exists).
[x] If this is a breaking change I've explained why.

graphile / crystal