draft: add jvm.fd.open and jvm.runtime.uptime to jmx configs

[schmikei]

Description:

WIP:

• adding jvm.runtime.uptime and jvm.fd.open to the jvm collectors

Existing Issue(s):

< Link any applicable issues. >

Testing:

< Describe what testing was performed and any tests were added. >

Documentation:

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Please be sure to modify relevant existing documentation if needed. >

Outstanding items:

< Anything that these changes are intentionally missing
that will be needed or can be helpful in the future. >

[SylvainJuge]

This PR adds metrics to the "JMX Gatherer", which should be replaced in a near/medium future with the new "JMX scraper".

When adding new metrics, you should also add them to the new YAML definitions https://github.com/open-telemetry/opentelemetry-java-contrib/blob/main/jmx-scraper/src/main/resources/jvm.yaml and also modify the related tests.

Also, adding those metrics to the "JMX Insight" feature of instrumentation would be nice to capture consistent metrics when using either of those implementations (Contrib JMX Gatherer, Contrib JMX Scraper or Instrumentation JMX Insights).

Last but not least, I haven't seen those metrics being defined in the Java runtime semconv. While the JMX metrics are currently not defined in semconv and are not strictly required to be, having at least some alignment with the current ones would help to provide a consistent experience and could help making them part of semconv later.

[trask]

adding jvm.runtime.uptime and jvm.fd.open to the jvm collectors

can you open an issue in https://github.com/open-telemetry/semantic-conventions to suggest these? it could probably use some discussion over there to align with naming conventions