WL#17342: Move authentication_webauthn to community edition

Webauthn authentication plugin provides ability to authenticate user using fido 
devices. It is useful both, as a method to achieve MFA and to achieve 
passwordless access.

The plugin is part of enterprise offering. This worklog tracks moving the plugin 
to community edition in Innovation releases.

FR1: Plugin authentication_webauthn should be available in MySQL Community 
Edition.

FR2: Relevant code and tests should be available as a part of source code - both 
on Github and as a part of source packages.

HLS1: The source code of authentication_webauthn will be moved to 
/plugin/authentication_webauthn

HLS2: Test cases for authentication_webauthn plugin will be moved to 
/mysql-test/suite/authentication_webauthn.

HLS2.1: Test cases that rely on other enterprise features will not be moved.

HLS3: Packaging scripts will be changed to make sure that 
authentication_webauthn plugin and relevant dependencies are part of server 
community packages.

HLS4: As a part of this work, we will also do some cleanup related to client 
side plugin - authentication_webauthn_client.

HLS4.1: Client side code will be moved from 
libmysql/fido_client/authentication_webauthn to libmysql/authentication_webauthn

HLS4.2: Files from libmysql/fido_client/common/ will be moved to 
libmysql/fido/authentication_webauthn and directory common will be removed