Changing UpdateData<T> to expand support for types with index signatures.

[MarkDuckworth]

This change relaxes UpdateData<T>, so that dot notation can be used to update types T where T contains an index signature. An example type T that this affects:

interface MyV10ServerType {
  indexed: {
    [name: string]: {
      booleanProperty: boolean,
      numberProperty: number
    }
  }
};

Without this change, dot notation can not be used to update field 'indexed.foo.booleanProperty'.

const update: UpdateData<MyV10ServerType> = {
  'indexed.foo.booleanProperty': true <-- TS2322: Type 'true' is not assignable to type '{ booleanProperty?: boolean | FieldValue | undefined; numberProperty?: number | FieldValue | undefined; } | FieldValue | undefined'.
}

updateDoc<MyV10ServerType>(docRef, update);

With this change, the following code is now possible:

const update: UpdateData<MyV10ServerType> = {
  'indexed.foo.booleanProperty': true
}

updateDoc<MyV10ServerType>(docRef, update);

The downside of this change is that we lose type safety and auto-complete for these types. For example we can do the following:

const update: UpdateData<MyV10ServerType> = {
  'indexed.foo': 'foo is not a string, it should be an object, but we can't enforce that...'
}

However, type safety and auto-complete are still in place if doing full object replacement:

// This is an example of update data that does a full object replacement
const update: UpdateData<MyV10ServerType> = {
  indexed: {
    foo: {
      booleanProperty: true,
      numberProperty: 1
    }
  }
}

And, we should note that type safety and auto complete are still in place for nested types when index signature is not involved.

interface NestedObject {
  indexed: {
    // see, no index signature on this line
    foo: {
      booleanProperty: boolean,
      numberProperty: number
    }
  }
};

const update: UpdateData<NestedObject> = {
  'indexed.foo.booleanProperty': true // we have type safety and auto-complete for this
}

Fixes #6105

Reviewers should understand that the unit tests in lite-api/types.test.ts are all new. These tests are introduced in a different pull request (7319) and are intended to ensure that UpdateData does not regress in unexpected ways with the fix in this PR.

[changeset-bot]

🦋 Changeset detected

Latest commit: 4ec7437

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 3 packages

Name	Type
@firebase/firestore	Minor
firebase	Patch
@firebase/firestore-compat	Patch

Not sure what this means? Click here to learn what changesets are.

Click here if you're a maintainer who wants to add another changeset to this PR

[google-oss-bot]

Size Report ¹

Affected Products

No changes between base commit (f2fb56f) and merge commit (ed7ab0e).

Test Logs

• Base (f2fb56f): https://github.com/firebase/firebase-js-sdk/actions/runs/5425726463
• Merge (ed7ab0e): https://github.com/firebase/firebase-js-sdk/actions/runs/5426676175

1. https://storage.googleapis.com/firebase-sdk-metric-reports/HX0X08mOAh.html

[google-oss-bot]

Size Analysis Report ¹

Affected Products

No changes between base commit (f2fb56f) and merge commit (ed7ab0e).

Test Logs

• Base (f2fb56f): https://github.com/firebase/firebase-js-sdk/actions/runs/5425726463
• Merge (ed7ab0e): https://github.com/firebase/firebase-js-sdk/actions/runs/5426676175

1. https://storage.googleapis.com/firebase-sdk-metric-reports/ZX9yxDIJyY.html

[dconeybe]

Thanks for this fix! I can't honestly say I completely understand it; however, the I understand the unit tests so it looks good to me!

[hsubox76]

Looks good, just needs a changeset (minor)

[dconeybe]

This was included in the v10.0.0 release: https://firebase.google.com/support/release-notes/js#version_1000_-_july_6_2023