[keyserver] Update types to remove any

Summary: Addressing review on D11780 - we want to remove any types in general

Test Plan: Tested that it is possible to login in single and multi keyserver setup. Assuming that siwe works by symmetry + by SIWEAuthRequest also including required fields

Reviewers: ashoat, tomek

Reviewed By: ashoat

Differential Revision: https://phab.comm.dev/D11895