[web] Include primaryIdentityPublicKey in SIWE message
Summary:
Include primaryIdentityPublicKey from olm in the SIWE message as we do on native. Note that this diff just includes getting the primaryIdentityPublicKey from olm and including it to the SIWE message statement.
NOTE: Persistence of the primaryIdentityPublicKey will happen in a subsequent diff.
Test Plan:
Works as expected, can see that the primaryIdentityPublicKey is included in the SIWE message and everything is validated on the keyserver side!
Reviewers: ashoat, tomek
Reviewed By: ashoat
Differential Revision: https://phab.comm.dev/D6410