glz::json_t trait support

[StormLord07]

• added a trait support for glz::json_t, map like glaze object jwt::traits::stephenberry_glaze
• and a default.h file

[Thalhammer]

Hi and thank you for showing interest in extending jwt-cpp's support for json libraries.
Would it be possible to add some CI testing to ensure we don't break any of the code in the future ?
In addition the CMake scripts need modification to ensure the new files are correctly installed along the other headers.

[StormLord07]

@Thalhammer I’ve added tests. Glaze is usually installed via FetchContent, but it can be found using find_package. I used find_package like in other tests, though it can't be installed via apt and has to be built from source and installed manually

A few points to mention:

1. glz::json_t doesn’t store integer values, only doubles. I didn’t add special support for integers. The only workaround I can think of is checking if double == floor(double), which feels wrong because we might want 16.0 to not be the same as 16.
2. There’s no support for string streams and operator>> with glz::json_t, so I had to change the test code. We could either add artificial support for it or i could try adding PR to Glaze, but that would take some time.

[StormLord07]

It should work, unfortunately i cant fix it without changing already exisiting ci too much, its just JWT CI coverage fails on

geninfo: ERROR: mismatched end line for _ZN25BaseTest_Base64Index_Test8TestBodyEv at /home/runner/work/jwt-cpp/jwt-cpp/tests/BaseTest.cpp:4: 4 -> 20
	(use "geninfo --ignore-errors mismatch ..." to bypass this error)

the fix should be changinx tests CMake file with provding additional args to
setup_target_for_coverage_lcov(NAME coverage EXECUTABLE ${CMAKE_CURRENT_BINARY_DIR}/jwt-cpp-test)

but

• im not sure how do it properly
• its outside of scope of this pr,

All other problems were mentioned before

1. glz::json_t doesn’t store integer values, only doubles. I didn’t add special support for integers. The only workaround I can think of is checking if double == floor(double), which feels wrong because we might want 16.0 to not be the same as 16.
2. There’s no support for string streams and operator>> with glz::json_t, so I had to change the test code. We could either add artificial support for it or i could try adding PR to Glaze, but that would take some time.

tests/traits/StephenberryGlazeTest.cpp:19
tests/traits/StephenberryGlazeTest.cpp:58

[Thalhammer]

Glaze is usually installed via FetchContent

Using FetchContent is also fine, we already do that for nlohmann json. If you do that it would be good to add a option to disable it so that people can turn it off if they don't want to use it.

so I had to change the test code.

That's perfectly fine for me. We don't guarantee/require any support from the json library except whats needed inside jwt-cpp or the trait itself.

its just JWT CI coverage fails on

Yeah that's known. Coverage broke a while ago due to version changes in githubs runners, I just haven't come around to update it yet. It's outside the scope of the PR, so don't worry about it ;)
If you are bored you are free to fix it in a different PR though.