Conditional trapping of inhibits; assertion; improve Relay NodeID compatibility

[benjie]

Description

Another PR relating to #2013; follow up to #2015.

For relay we need to be able to support a query like this:

query Q($authorId: ID) {
  allPosts(condition: { author: $authorId }) {
    nodes {
      body
    }
  }
}

When we do this, what we want changes based on the value of $authorId:

• $authorId undefined: no condition applied, select all posts (WHERE true)
• $authorId null: find posts which have no author (WHERE author_id is null)
• $authorId valid Author ID: find posts by this author (WHERE author_id = $1)
• $authorId is invalid or references the wrong type: raise an error to inform the user of their mistake

It wasn't possible to do this in plans previously (you had to do it in the step class' execute method instead, like with a resolver) but this PR makes it possible as demonstrated by the changes to PgNodeIdAttributesPlugin.

Note that this.addDependency(step, true) is no longer supported; instead you must use this.addDependency({ step, skipDeduplication: true }). I doubt this affects many people.

Performance impact

Unknown.

Security impact

None known.

Checklist

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

[changeset-bot]

🦋 Changeset detected

Latest commit: cf8af9d

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 15 packages

Name	Type
grafast	Patch
graphile-build-pg	Patch
postgraphile	Patch
@dataplan/pg	Patch
@localrepo/grafast-bench	Patch
@dataplan/json	Patch
@grafserv/persisted	Patch
grafserv	Patch
ruru-components	Patch
@localrepo/grafast-website	Patch
graphile-build	Patch
graphile-utils	Patch
pgl	Patch
graphile-export	Patch
graphile	Patch

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