[io][json] store inf, nan as strings and read them back properly

[ferdymercury]

Fixes #19768

[ferdymercury]

I need some help with the Test. It works fine if I run it by copy-pasting it into the interpreter. So it seems like a missing dict that I did not manage to generate well in the scripted version.

[github-actions]

Test Results

    22 files      22 suites   4d 1h 43m 44s ⏱️
 3 692 tests  3 645 ✅ 0 💤 47 ❌
79 270 runs  79 173 ✅ 0 💤 97 ❌

For more details on these failures, see this check.

Results for commit 73751b2.

♻️ This comment has been updated with latest results.

[linev]

Proposed approach is not portable.

So any other JSON parser will fail completely parsing such string - and not only this single member.
JSON normally not used for objects I/O inside ROOT but rather for data exchange with other applications.

So provided solution can be used - but not by default.
One can provide special flag in compact argument to enable such feature.
See TBufferJSON.h around lines 35 - 48.
Something like kStoreInfinity = 500.
And then adjust TBufferJSON::SetCompact method.

[ferdymercury]

CI is finally green :)

[linev]

This looks fine for me