refactor(account-tree-controller): add type field for each tree node + improve typing overall (#6214)

## Explanation

Add new `type` field for each wallets/groups.

This is used as a "tag", so proper node types can be inferred by the
compiler.

e.g:
```ts
// Using wallet as root node:
if (wallet.type === AccountWalletType.Entropy) {
  console.log(wallet.metadata.entropy.id);

  // This `wallet` is narrowed down to `AccountWalletEntropyObject`, it knows that
  // `wallet.groups` are `AccountGroupMultichainAccountObject`, so we can use
  // the `groupIndex` safely here too.
  for (const group of Object.values(wallet.groups)) {
    console.log(group.metadata.entropy.groupIndex);
  }
}

if (wallet.type === AccountWalletType.Snap) {
  console.log(wallet.metadata.snap.id);
}

if (wallet.type === AccountWalletType.Keyring) {
  console.log(wallet.metadata.keyring.type);
}

// Using group as root node:
if (group.type === AccountGroupType.SingleAccount) {
  // No real metadata for this, however, we enforced the `accounts` to be
  // a `[AccountId]` tuple, so it is safe to do:
  console.log(group.accounts[0]);
  
  // And this should not build:
  console.log(group.accounts[1]); // ERROR: Tuple type '[string]' of length '1' has no element at index '1'.
}

if (group.type === AccountGroupType.MultichainAccount) {
  console.log(group.metadata.groupIndex);
  
  // For multichain accounts group we have "at least 1" account, but we could have more.
  console.log(group.accounts[0]);
  console.log(group.accounts[1]); // Assuming we have 2 accounts here.
}
```

## References

N/A

## Changelog

N/A

## Checklist

- [x] I've updated the test suite for new or updated code as appropriate
- [x] I've updated documentation (JSDoc, Markdown, etc.) for new or
updated code as appropriate
- [ ] I've communicated my changes to consumers by [updating changelogs
for packages I've
changed](https://github.com/MetaMask/core/tree/main/docs/contributing.md#updating-changelogs),
highlighting breaking changes as necessary
- [ ] I've prepared draft pull requests for clients and consumer
packages to resolve any breaking changes

Author: ccharly

packages/account-tree-controller/CHANGELOG.md

@@ -7,8 +7,18 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Added
+
+- Add `group.type` tag ([#6214](https://github.com/MetaMask/core/pull/6214))
+  - This `type` can be used as a tag to strongly-type (tagged-union) the `AccountGroupObject`.
+- Add `group.metadata` metadata object ([#6214](https://github.com/MetaMask/core/pull/6214))
+  - Given the `group.type` you will now have access to specific metadata information (e.g. `groupIndex` for multichain account groups)
+
 ### Changed
 
+- **BREAKING:** Bump peer dependency `@metamask/account-api` from `^0.3.0` to `^0.5.0` ([#6214](https://github.com/MetaMask/core/pull/6214))
+- **BREAKING:** Move `wallet.metadata.type` tag to `wallet` node ([#6214](https://github.com/MetaMask/core/pull/6214))
+  - This `type` can be used as a tag to strongly-type (tagged-union) the `AccountWalletObject`.
 - Defaults to the EVM account from a group when using `setSelectedAccountGroup` ([#6208](https://github.com/MetaMask/core/pull/6208))
   - In case no EVM accounts are found in a group (which should not be possible), it will defaults to the first account of that group.
 

packages/account-tree-controller/package.json

@@ -53,7 +53,7 @@
     "lodash": "^4.17.21"
   },
   "devDependencies": {
-    "@metamask/account-api": "^0.3.0",
+    "@metamask/account-api": "^0.5.0",
     "@metamask/accounts-controller": "^32.0.1",
     "@metamask/auto-changelog": "^3.4.4",
     "@metamask/keyring-api": "^19.0.0",
@@ -70,7 +70,7 @@
     "webextension-polyfill": "^0.12.0"
   },
   "peerDependencies": {
-    "@metamask/account-api": "^0.3.0",
+    "@metamask/account-api": "^0.5.0",
     "@metamask/accounts-controller": "^32.0.0",
     "@metamask/keyring-controller": "^22.0.0",
     "@metamask/providers": "^22.0.0",