Use import type in typescript for all imports

[tomgasson]

This makes the following change to typescript artifacts:

-import { ConcreteRequest, Query } from "relay-runtime";
+import type { ConcreteRequest, Query } from "relay-runtime";
 import type { FragmentRefs } from "relay-runtime";

Using the existing useImportTypeSyntax config.

As stated in the config, the import type syntax introduced in Typescript version 3.8 and prevents warnings from importsNotUsedAsValues. This setting also assists naive bundlers from taking a dependency on relay-runtime, when only the types are needed.

I kept this simple. Other paths for implementation would be

• There's a mix of distinct typegen printers e.g. compiler/crates/relay-typegen/src/typescript.rs, and the inline use of conditionals on the language directly in compiler/crates/relay-compiler/src/artifact_content/content.rs. Consolidating these would allow sharing the existing write_import_type function
• The imports could instead be consolidated and printed together, rather than potentially having multiple imports from the same file as it is now

[alunyov]

Thank you for PR! This looks good to me!

Can you add a test for these changes?

[tomgasson]

This is the only difference to the typescript fixtures. I wasn't able to use the %project_config% form of specifying the config in each, because that ends up in a dependency cycle.

The fixtures in relay_codegen also aren't quite appropriate, because they only check the metadata content, not the entire file, and I need to check the imports

Those "other paths for implementation" mentioned would cover where this is done, but would be a significant reshuffle of code

[facebook-github-bot]

@alunyov has imported this pull request. If you are a Meta employee, you can view this diff on Phabricator.

[facebook-github-bot]

@alunyov has imported this pull request. If you are a Meta employee, you can view this diff on Phabricator.

[tomgasson]

Removed the missing newline at EOF, because I'm guessing that was the internal lint warning

[alunyov]

Hmm, @tomgasson for some reason this breaks one of the internal typescript tests (we should probably move these to OSS)

It removes the import type of ConcreteRequest and Query...

/* eslint-disable */
 // [@ts](https://www.internalfb.com/intern/profile/ts)-nocheck
 
-import { ConcreteRequest, Query } from 'relay-runtime';

[tomgasson]

Hmmm. Are those tests using use_import_type_syntax? Is the output after stripping types / building typescript artifacts? That's kind of the purpose of this change - to not have a value import in the code actually sent to browsers

It's a bit hard to see how this change would remove something if it's only the relay generated output