Post-request filter queries#11

It would be a really powerful addition to the extension if the resulting JSON output could be further filtered for attribute values when the requested GraphQL API does not support filtering by that attribute value. I can give an example: The GitHub API does not support listing repository PRs that changed a specific file. It can only list all files changed by all open PRs: ``` query { repository(owner: "myowner", name: "myrepository") { pullRequests(first: 100, states: OPEN) { nodes { permalink files(first: 100) { nodes { path } } } } } } ``` resulting in: ``` { "repository": { "pullRequests": { "nodes": [ { "permalink": "https://github.com/myowner/myrepository/pull/123", "files": { "nodes": [ { "path": "README.md" }, ... ] } }, ... ] } } } ``` I am not sure if there is any standardized format how to specify such post-filter queries but if I'd stick to GraphQL syntax, it could be specified e.g. as: ``` filter { repository { pullRequests { nodes { permalink where(path: "files.nodes.path", operation: Equals, value: "README.md") } } } } ``` resulting in: ``` { "repository": { "pullRequests": { "nodes": [ { "permalink": "https://github.com/myowner/myrepository/pull/123" } ] } } } ```