Provide within-process "public" API for fiber dumps

[armanbilge]

trafficstars

For environments without signals or JMX ... that would be Windows/GraalVM and browsers?

[armanbilge]

"public" b/c @vasilmkd proposed the duck-typing trick.

[armanbilge]

From this discussion on Discord another use-case for this would be when creating a custom IORuntime outside of IOApp since neither mbeans nor signals are registered in that case.

[armanbilge]

Another Discord discussion, considering ideas to integrate fiber dumps with test suites via this API.