chore: update generated array type definitions in TypeScript to be readonly

[Emyrk]

No issue to link – this was a pain point when trying to bring the Coder generated types into Backstage as an SDK (similar to how the VS Code extension is doing things).

Changes

• Updates type-generation logic on the Go side to make all TypeScript arrays be readonly (see notes)
• Updates all UI code in TypeScript to remove any mutable array types, and remove accidental runtime mutations

Notes

Before, we had types like this:

interface Value {
  readonly workspaces: Workspace[];
}

With this, type Value's workspaces property can't be reassigned, but the underlying array is still fully mutable. TypeScript is perfectly happy with this:

function doStuff (value: Value) {
  const newWorkspace = makeWorkspace();
  value.workspaces.push(newWorkspace);
}

With the update, the type definitions now look like this:

interface Value {
  readonly workspaces: readonly Workspace[];
}

Both the property on the object, and the array the property points to are readonly

function doStuff (value: Value) {
  const newWorkspace = makeWorkspace();
  
  // TypeScript compiler complains
  value.workspaces.push(newWorkspace);
  
  // Perfectly fine
  const workspacesCopy = [...value.workspaces];
  workspacesCopy.push(newWorkspace);
}

Especially since both React and React Query are built around the assumption that 99% of their data is fully immutable, accidental mutations have a risk of introducing bugs that would be incredibly hard to track down

[Parkreiner]

This is the only change – check that proxies is defined, and then if it is, spread it into a new array, and mutate that instead of the original

All the other code is exactly the same

[Parkreiner]

Not for the future: R extends any actually doesn't do anything at all. Since any is a top type, everything in TypeScript extends any, so the type constraint provides zero protection

At some point, we'd probably want to turn this into

export interface Foo<R = unknown> {
  // Stuff
}

[Parkreiner]

Double-checked everything, as well as the story changes, and nothing seems to have gone awry.

My main worry at first was that removing some of the accidental mutations would break things, but we just happened to luck into the mutations causing really small, imperceivable changes. Definitely no-nos as far as React best practices, but we cut them off before they could do anything really nasty