Allow square bracket in JMX config value

[eyalkoren]

What does this PR do?

Closes #2527
Allows square brackets within the JMX config option value, e.g.

object_name[amx:pp=/mon/server-mon[server],type=...] attribute[...] 

@felixbarny is there a reason not to allow that?

Checklist

• This is an enhancement of existing features, or a new feature in existing plugins
  • I have updated CHANGELOG.asciidoc
  • I have added tests that prove my fix is effective or that my feature works
  • I have made corresponding changes to the documentation

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• Start Time: 2022-04-04T14:39:21.243+0000

• Duration: 45 min 11 sec

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Test	Results
Failed	0
Passed	2842
Skipped	20
Total	2862

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