Add support for simplecov-json in simplecov parser

[marschattha]

Some customers are reported to be using simeplcov-json gem to generate coverage report, which generates it differently from the current and legacy simplecov format that we current support, this PR adds support for simplecov-json format.
https://github.com/vicentllongo/simplecov-json

[qltysh]

Diff Coverage: The code coverage on the diff in this pull request is 97.6%.

Total Coverage: This PR will increase coverage by 0.04%.

File Coverage Changes

Path	File Coverage Δ	Indirect
qlty-check/src/executor/driver.rs	-0.9	√
qlty-check/src/tool/command_builder.rs	2.6	√
qlty-check/src/tool/download.rs	0.7	√
qlty-check/src/tool/ruby/sys/linux.rs	-1.6	√
qlty-check/src/tool/ruby/sys/macos.rs	3.1	√
qlty-cli/src/initializer/scanner/gemfile.rs	0.3	√
qlty-cloud/src/auth/auth_flow.rs	-0.5	√
qlty-config/src/library.rs	0.5	√
qlty-coverage/src/parser/simplecov.rs	0.1

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• Diff Coverage: Coverage for added or modified lines of code (excludes deleted files). Learn more.

• Total Coverage: Coverage for the whole repository, calculated as the sum of all File Coverage. Learn more.

• File Coverage: Covered Lines divided by Covered Lines plus Missed Lines. (Excludes non-executable lines including blank lines and comments.)

  • Indirect Changes: Changes to File Coverage for files that were not modified in this PR. Learn more.

[brynary]

Am I reading this correctly that the single Simplecov parser will now auto-detect "regular"/legacy simplecov vs simplecov-json?

[marschattha]

Yes, should we add it as a separate parser?
Might make things difficult on auto detect.

Previously we were only detecting simplecov and legacy simplecov format and if we got neither it would return empty.
This PR adds a third state(simplecov-json) if first two fail before returning empty if none.