Fix dpctl.lsplatform() to output in jupyter notebook

[vlad-perevezentsev]

Closes #796

This PR changes DPCTLPlatformMgr_PrintInfo function to return char * instead of outputting it in libsyclinterface , and use that to print using CPython.

[oleksandr-pavlyk]

Please do not change the API public functions. Instead extend the API and change the implementation of the API.

DPCTLPlatformMgr_PrintInfo calls internal routine to get std::string and outputs it as before.
DPCTLPlatformMgr_GetInfo calls internal routine to get std::string and copies the result into C-style string.

[github-actions]

View rendered docs @ https://intelpython.github.io/dpctl/pulls/800/index.html

[coveralls]

Coverage increased (+0.04%) to 82.105% when pulling 49e3419 on fix_lsplatform into a20344b on master.

[oleksandr-pavlyk]

@vlad-perevezentsev Thank you for making the requested changes. DPCTLSyclInterface tests for DPCTLPlatformMgr_GetInfo are also needed.

The test would call a function and check that the returned const char * is not a nullptr.

[oleksandr-pavlyk]

I was able to build the coverage workflow manually. I was also able to manually confirm that the original issue of output of dpctl.lsplatform() not showing in remotely connected jupyter notebook has been fixed.

LGTM! Waiting for the CI to run its course.

[github-actions]

Deleted rendered PR docs from intelpython.github.com/dpctl, latest should be updated shortly. 🤞