TypeScript strict mode support + docs

[dac09]

Background

If you turn on TypeScript strict mode, (modify tsconfig.json)

{
  "compilerOptions": {
    "noEmit": true,
    "allowJs": true,
+    "strict": true,

Redwood projects currently have a bunch of errors, with no clear path to a solution.

This PR is a combination of documentation, exporting and adding more types so that users opting-in to strict mode can have an error free project. Note that we are not enabling strict mode by default.

Changes in this PR

Generate stricter Resolver definitions in strict mode

• When strict mode is turned on, make "args" of each of the resolvers (i.e. service functions) non-optional
• Document changes to service tests to remove errors

src/lib/auth.ts

• Documentation on how to get rid of the errors related to roles checks in src/lib/auth
• Add types for getCurrentUser for non-dbAuth - this really is too hairy

dbAuth

• Make DbAuthOptions and DbAuthSession available for users to import in their project.
• Updates default generated templates in src/lib/auth and src/functions/auth to use these types
• Allow generics, so the "user" in dbAuth can be typed
• Documentation on how to use the generics
• Add a line to setup auth dbAuth output on "using dbAuth with TS" generator output is already too verbose

Relation resolvers
When you have a model with a relation, and you generate the sdl or service with the --crud flag, relational resolvers are generated.

• Changes the generator templates to use optional chaining to access gqlArgs.
  Reasoning:
  a) Although these are resolvers, they can be used outside the graphql context - where gqlArgs aren't passed.
  b) The alternative is to ask users to modify all their service tests. Its ugly and confusing and unnecessary.
• Update graphql resolver docs

Prisma vs Graphql null types

• Document that Prisma differentiates between null and undefined (https://www.prisma.io/docs/concepts/components/prisma-client/null-and-undefined) and recommend Orta's suggestion to use dnull in this section
• Add example using dnull
• Create issue for adding dnull to Redwood templates by default

Avoid optional resolvers types
This is a codegen config change (see graphqlCodegen.ts)

• Make generated Resolver types non-optional, so they do not complain in strict mode

Improve return type of Scenarios

• Expose ScenarioData type that lets you define exactly what the output of a scenario is
• Add backlink here to scenario typing docs

Service tests with chained calls

• Change template for service/scenario tests to tell TS to pipe down

Prisma findUnique return types
❌ No solution, just have to document

Closes #5481
Closes #5463
Closes #5261

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[dac09]

Related issues:

• mockCurrentUser does not type-check as expected with TypeScript's strict option #5261
• export dbAuth Types #5463

Addressed comments