add pioasm --version, and print version number in generated files

[kilograham]

fixes #2307

[lurch]

Is the change to amethyst.pio here intentional, or is that part of #2338 ?
This LGTM, but I won't approve because CI is failing 😉

@will-v-pi I wonder if it's worth having a CI job that builds a sample PIO file with each of the different output-formats that pioasm supports (ideally covering as many PIO keywords as possible?), and then comparing those newly-created outputs to "known good" output files?

Also, after this PR is merged I guess we'll need to update the pioasm-generated headers in the pico-examples repo.

[lurch]

I wonder if it might be worth also including the filename (with any directory-parts removed) of the input PIO file? e.g.

// This file is autogenerated from ws2812.pio by pioasm version 2.1.2; do not edit!

[kilograham]

Is the change to amethyst.pio here intentional, or is that part of #2338 ? This LGTM, but I won't approve because CI is failing 😉

@will-v-pi I wonder if it's worth having a CI job that builds a sample PIO file with each of the different output-formats that pioasm supports (ideally covering as many PIO keywords as possible?), and then comparing those newly-created outputs to "known good" output files?

Also, after this PR is merged I guess we'll need to update the pioasm-generated headers in the pico-examples repo.

it was unintentional, but then again the file isn't really used for anything - we should have a regression test that checks the output

[will-v-pi]

LGTM - I will fix pico-sdk-tools to pass the new PIOASM_VERSION_STRING argument