Developer documentation and scripts require updating following Companion upgrade to Qt 5.15.2 and other cumulative changes

[elecpower]

Is there an existing issue for this problem?

• [X] I have searched the existing issues

What part of EdgeTX is the focus of this bug?

Build system

Current Behavior

Setting up build toolchains and self compiling documentation is out of date

Expected Behavior

Documentation and scripts should facilitate self building radio firmware and Companion

Steps To Reproduce

1. Follow existing documentation
2. Compilation fails

Version

Nightly (Please give date/commit below)

Transmitter

Other (Please specify below)

Operating System (OS)

Linux, macOS, Windows

OS Version

No response

Anything else?

No response

[pfeerick]

#4314 is related to this