fix: add password recoery flow support for pkce (#813)

## What kind of change does this PR introduce?

Currently, `PASSWORD_RECOVERY` auth event is not emitted during a
password recovery flow using pkce.

## What is the current behavior?

Calling `resetPasswordForEmail()` method 

## What is the new behavior?

Calling `resetPasswordForEmail()` sets a code verifier and the auth flow
`PASSWORD_RECOVERY` with a `/` separator on the local storage like this:
`${codeVerifier}/PASSWORD_RECOVERY`

Within `_exchangeCodeForSession()`, the auth flow and the code verifier
is extracted from local storage, and if the auth flow is
`PASSWORD_RECOVERY`, then `PASSWORD_RECOVERY` event is fired instead of
`SIGNED_IN` event.

src/GoTrueClient.ts

@@ -499,8 +499,16 @@ export default class GoTrueClient {
     })
   }
 
-  private async _exchangeCodeForSession(authCode: string): Promise<AuthTokenResponse> {
-    const codeVerifier = await getItemAsync(this.storage, `${this.storageKey}-code-verifier`)
+  private async _exchangeCodeForSession(authCode: string): Promise<
+    | {
+        data: { session: Session; user: User; redirectType: string | null }
+        error: null
+      }
+    | { data: { session: null; user: null; redirectType: null }; error: AuthError }
+  > {
+    const [codeVerifier, redirectType] = (
+      (await getItemAsync(this.storage, `${this.storageKey}-code-verifier`)) as string
+    ).split('/')
     const { data, error } = await _request(
       this.fetch,
       'POST',
@@ -516,15 +524,18 @@ export default class GoTrueClient {
     )
     await removeItemAsync(this.storage, `${this.storageKey}-code-verifier`)
     if (error) {
-      return { data: { user: null, session: null }, error }
+      return { data: { user: null, session: null, redirectType: null }, error }
     } else if (!data || !data.session || !data.user) {
-      return { data: { user: null, session: null }, error: new AuthInvalidTokenResponseError() }
+      return {
+        data: { user: null, session: null, redirectType: null },
+        error: new AuthInvalidTokenResponseError(),
+      }
     }
     if (data.session) {
       await this._saveSession(data.session)
       await this._notifyAllSubscribers('SIGNED_IN', data.session)
     }
-    return { data, error }
+    return { data: { ...data, redirectType: redirectType ?? null }, error }
   }
 
   /**
@@ -1538,7 +1549,11 @@ export default class GoTrueClient {
     let codeChallengeMethod: string | null = null
     if (this.flowType === 'pkce') {
       const codeVerifier = generatePKCEVerifier()
-      await setItemAsync(this.storage, `${this.storageKey}-code-verifier`, codeVerifier)
+      await setItemAsync(
+        this.storage,
+        `${this.storageKey}-code-verifier`,
+        `${codeVerifier}/PASSWORD_RECOVERY`
+      )
       codeChallenge = await generatePKCEChallenge(codeVerifier)
       codeChallengeMethod = codeVerifier === codeChallenge ? 'plain' : 's256'
     }