[native] Include signedIdentityKeysBlob in login/register/siwe_auth requests

Summary:
Modify nativeLogInExtraInfoSelector so it includes signedIdentityKeyBlob instead of primaryIdentityPublicKey.

Also some misc changes to remove old primaryIdentityPublicKey stuff and to allow signedIdentityKeyBlob in registerRequestInputValidator.

Next diff will include signedIdentityKeysBlob in createAccount and we should be good.

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Depends on D6822

Test Plan:
Successfully able to login, register, and SIWE. Set breakpoints and observed that signedIdentityKeysBlob was included in requests.

Login:

Register:

SIWE:

Reviewers: ashoat, tomek, varun, jon

Reviewed By: varun

Differential Revision: https://phab.comm.dev/D6915