feature: add postgraphile-tag-json-tools for json schema generation

[phryneas]

Like requested in #205

Description

This PR only uses the createJsonSchema part of postgraphile-tag-json-tools, as extractSmartTags and loadSmartTags functionalities do not seem necessary here.

Changes in the database will update @app/server/pg-database-smart-tags.schema.json, but edits in @app/server/pg-smart-tags.schema.json will persist, so additional tags can be added without fear of something being overridden. (I added simpleCollections and resultFieldName, as I didn't have those in my initial schema - if you can think of any more tags, please mention them & I will add them.)

I've marked the place to add new tags with "$comment": "------ Add extra tags here, in properties. ------",.

Performance impact

None in production use, probably neglectable in dev mode.

Security impact

None in production use, nothing I could think of in dev use.

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.

[benjie]

This is really cool! It could do with a smidge of docs; could you put some in the @app/server/README.md file referencing the two newly created file names and a link to postgraphile-tag-json-tools please?

[benjie]

Avoiding the negative makes this easier to read IMO.

Suggested change

	...(!isDev
	? []
	: [
	// updates the `pg-database-smart-tags.schema.json` file based on the database
	CreateJsonSchemaPlugin,
	]),
	...(isDev
	? [
	// updates the `pg-database-smart-tags.schema.json` file based on the database
	CreateJsonSchemaPlugin,
	]
	: []),