Support unit testing on Windows

[adbancroft]

Unit tests failed to compile on Windows, using both the native (using MinGW-x64 v12.2.0) and windows_x86 platforms: in both cases the linker generated file too big errors.

• Solution is to move the tests out of line. I.e. from .h to .cpp files.
• The PR also adds a Win32 environment, which uses the standard platformio windows_x86 platform: this avoids having to install the native tool chain, which is a little cumbersome on Windows (one less barrier for developers).

[adbancroft]

The existing cmake config expects one test cpp... ☹️

Could we change to platformio test runner?

[adbancroft]

@FabioBatSilva I can add a PR to change the GitHub unit test action to run tests using platformio.

[FabioBatSilva]

Thanks @adbancroft
If the test pass on both linux and windows that sounds reasonable.

For what it's worth I remember running into some limitations that forced into the cmake path.
But I'ts been a while, It might not be a problem anymore.

[adbancroft]

Thanks @adbancroft If the test pass on both linux and windows that sounds reasonable.

For what it's worth I remember running into some limitations that forced into the cmake path. But I'ts been a while, It might not be a problem anymore.

Done - see #74. I'll update this PR when you accept #74