⚠️ Random user name generator 🎲

In many online service contexts, _**the user name is an e-mail address**_. When a free web service requires e-mail address validation but there is some risk that the address could be stolen or sold, some users will generate random addresses from the same domain to facilitate registration without compromising the privacy of their personal e-mail account. In this situation it would be convenient to have an automatic user name generator that works exactly like the password generator (except that the first random character will always be alphabetic.)

Start by locating the existing password generator in the KeePassDX Android application and understanding how its generated values are exposed to users. Add a corresponding random user name generator whose first character is alphabetic, then verify that it behaves like the password generator while preserving the stated e-mail registration use case.

Written by the indexing model from the issue text.