Add 64 bit image builds separately

[freerainboxbox]

April 18th, 2024 TF2 Update adds official 64-bit builds for both client and server

Build pipeline should have separate tags for 64-bit builds.

There's currently little to no documentation on how to run the server in 64-bit mode, but this issue should be watched.

[garrappachc]

Yup, base image can be already built, but sourcemod-based images need to have proper DHooks support

[garrappachc]

Support for the tf2-base image is added in https://github.com/melkortf/tf2-servers/pull/158