[lib][native][web] Move useLegacyAshoatKeyserverCall to lib/keyserver-conn/legacy-keyserver-call.js

Summary:
lib/utils/action-utils.js used to be a huge, unwieldy file. Now all that's left is useLegacyAshoatKeyserverCall, so the file can be renamed.

Additionally, I'm moving it into lib/keyserver-conn. Given the name and function, that seems like a better place, especially since useKeyserverCall was moved there as well in the prior diff.

Depends on D11699

Test Plan: Flow

Reviewers: tomek, inka

Reviewed By: tomek

Differential Revision: https://phab.comm.dev/D11700