Update passwordless docs with Android examples (aws-amplify#8139)

* Add initial android sign in doc updates

* Add sign in with preferred challenge

* Finish adding the non-webauthn sign in docs

* Add passwordless sign in docs into the multi-step-sign-in page

* Update manage-webauthn-credentials/index.mdx for android

* Add callingActivity to associateWebAuthnCredential examples

* Bring android sign-in docs to parity

* Add Android docs for switching authentication flows

* Add USER_AUTH password to the sign in docs

* Update sign up docs

* Add Android's WebAuthn details to `connect-your-frontend/sign-in/index.mdx`

* Fix some small issues and update multi-step sign in

* Add first factor selection section for android after merge

* Update src/pages/[platform]/build-a-backend/auth/connect-your-frontend/multi-step-sign-in/index.mdx

Co-authored-by: josef <[email protected]>

* Update src/pages/[platform]/build-a-backend/auth/connect-your-frontend/multi-step-sign-in/index.mdx

Co-authored-by: josef <[email protected]>

* Apply suggestions from code review

Co-authored-by: josef <[email protected]>

* Replace usages of username with email

* Update src/pages/[platform]/build-a-backend/auth/connect-your-frontend/sign-in/index.mdx

Co-authored-by: James Jarvis <[email protected]>

* Update index.mdx

---------

Co-authored-by: Matt Creaser <[email protected]>
Co-authored-by: josef <[email protected]>
Co-authored-by: James Jarvis <[email protected]>

Author: 4 people

cspell.json

@@ -1616,7 +1616,8 @@
     "jamba",
     "webauthn",
     "knowledgebases",
-    "rehype"
+    "rehype",
+    "assetlinks"
   ],
   "flagWords": ["hte", "full-stack", "Full-stack", "Full-Stack", "sudo"],
   "patterns": [