Add library CI support

[mikee47]

This PR provides an appveyor script and makefile to support standalone integration testing for libraries.

It builds all samples and tests against the Sming develop branch from the source repository.
This takes considerably less time and consumes less CI resource than a full Sming CI build, which may not be necessary.

See Tools/ci/library/README.rst for details.

Example run https://ci.appveyor.com/project/mikee47/FlashString/history

[slaff]

The Basic_NFC sample stopped compiling for Esp32 architectures.

A fatal error occurred: Segment loaded at 0x4200ca6e lands in same 64KB flash mapping as segment loaded at 0x42000020. Can't generate binary. Suggest changing linker script or ELF to merge sections.
make[2]: *** [/home/appveyor/projects/sming-sb483/Sming/Arch/Esp32/app.mk:28: out/Esp32/esp32c3/debug/firmware/app.bin] Error 2
make[1]: *** [/home/appveyor/projects/sming-sb483/Sming/project.mk:22: all] Error 2
make: *** [Makefile:121: /home/appveyor/projects/samples/Basic_NFC/.esp32c3.built] Error 2
Command exited 

Can you take a look at the failing tests in appveyor?

[mikee47]

The Basic_NFC sample stopped compiling for Esp32 architectures.

I broke it in #2429 when introducing setenv.ps1, used dev branch for esp idf instead of release.