Configure Tomcat server explicitly

Summary:
Use the default current Tomcat server.xml configuration from Orbeon container.

Credentials are stored in tomcat-users.xml with SHA-256 digest for hashing,
with a bruteforce protection.

Ref T2143

Test Plan: Redeploy Orbeon container and associated files

Reviewers: DorianWinty

Maniphest Tasks: T2143

Differential Revision: https://devcentral.nasqueron.org/D3755