[cpp headers] replace header guards with #pragma once

[xmkg]

This PR replaces all instances of header guards with much simpler and widely supported #pragma once.

MULTI-1995

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 89.31%. Comparing base (9cd0fa3) to head (15cdbb8).
⚠️ Report is 474 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #4090   +/-   ##
=======================================
  Coverage   89.31%   89.31%           
=======================================
  Files         259      259           
  Lines       15715    15715           
=======================================
  Hits        14036    14036           
  Misses       1679     1679           

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[xmkg]

LGTM, but it looks like a bunch of those files have space errors that are tripping up linting. Want to fix them too?

Done!

[ricab]

Hey @xmkg, I am afraid this will need another go 💦

[xmkg]

Hey @xmkg, I am afraid this will need another go 💦

No worries. I anticipated friction between the line-length branch and this one. Rebased to main, let's see if everything's still fine.

[Sploder12]

Great work! Neat to see this fixes some cases of bad header guards and missing copyrights too. But, you missed MULTIPASS_BLUEPRINTS_TEST_LAMBDAS_H ;)

[xmkg]

But, you missed MULTIPASS_BLUEPRINTS_TEST_LAMBDAS_H ;)

Nah, that doesn't count... That's a source guard -- protecting against double inclusion of a source file. This PR is header guards only...

Just joking 😛 Probably somebody copied this from a header and forgot to remove the guard. I'll remove it :) Good catch!

[xmkg]

BTW, I intentionally left the Flutter GUI header guards in place since some of them are generated code, and the rest is copied from the example app.

[xmkg]

Great work! Neat to see this fixes some cases of bad header guards and missing copyrights too. But, you missed MULTIPASS_BLUEPRINTS_TEST_LAMBDAS_H ;)

Done!

[Sploder12]

Nah, that doesn't count... That's a source guard -- protecting against double inclusion of a source file. This PR is header guards only...

I completely missed that was from a .cpp, interesting...

[ricab]

Alright, thanks for this!

[epicseven-cup]

I like this pr