Replace CMake generated version files with checked-in versions

[darbyjohnston]

In PR #1907 we added version headers so applications could identify which OpenTimelineIO they were using. However this also introduced a dependency on CMake to generate the headers, which can cause issues for other projects that use OTIO without CMake (for example the OTIO Swift bindings).

This PR replaces the CMake file generation with checked-in files, and instead has CMake parse the version from the checked-in header files. This is similar to what OpenEXR does for their version handling.

[meshula]

looking good, minor request

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 85.15%. Comparing base (f2b7693) to head (0bb458e).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1993   +/-   ##
=======================================
  Coverage   85.15%   85.15%           
=======================================
  Files         181      181           
  Lines       12783    12783           
  Branches     1206     1206           
=======================================
  Hits        10885    10885           
  Misses       1715     1715           
  Partials      183      183           

Flag	Coverage Δ
py-unittests	85.15% <ø> (ø)

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[meshula]

Sorry, I don't know how I typed 4 #'s in a row. I'm still in favor of concatenation even with a helpy macro!

[darbyjohnston]

Sorry, I don't know how I typed 4 #'s in a row. I'm still in favor of concatenation even with a helpy macro!

That requires updating every source file with the new macro. That seems like a lot of work to not duplicate a number, plus it also adds complexity which I think undermines the benefits of DRY.

[jminor]

Trying this PR out on the Swift bindings here: OpenTimelineIO/OpenTimelineIO-Swift-Bindings#78

[jminor]

This seems to be working well for the Swift bindings.

Related: I noticed one typo in the README.md which says

namespace otio = opentimelineio::OPENTIMELINEIO_VERSION;

but I think it should be

namespace otio = opentimelineio::OPENTIMELINEIO_VERSION_NS;

[darbyjohnston]

Good catch, I updated the example code to use our namespace macro OTIO_NS.

[jminor]

Oh cool. I'll update the Swift bindings to use that macro too.

@meshula are you okay if we skip your suggestion about the ## macro concatenation?

[meshula]

fancy macros don't block merging, thanks for the PR!