8237: Add support for Jolokia over Kubernetes proxy

[skarsaune]

JMC-8273 : Use the jolokia protocol over a kubernetes http proxy.

Testing connectivity:

• [x] Docker desktop kubernetes
• [x] Azure AKS
• [ ] Amazon EKS
• [ ] Google GKE

Other things observed:

• [ ] * Option to install agent should be disabled (debug difference with jolokia)
• [ ] * Warning: NLS missing message: JmcKubernetesPreferenceForm_LogErrorsTooltip in: org.openjdk.jmc.kubernetes.preferences.messages
• [ ] * SLF4J(W): No SLF4J providers were found. SLF4J(W): Defaulting to no-operation (NOP) logger implementation SLF4J(W): See https://www.slf4j.org/codes.html#noProviders for further details.
• [x] Unlocking secrets now appear on startup. Should not be needed unless there are credentials used. (fixed)

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Progress

• [x] Commit message must refer to an issue
• [ ] Change must be properly reviewed (1 review required, with at least 1 Committer)

Issue

• JMC-8237: Add support for Jolokia over Kubernetes proxy (Enhancement - P4)

Reviewing

Using git

Checkout this PR locally:
$ git fetch https://git.openjdk.org/jmc.git pull/576/head:pull/576
$ git checkout pull/576

Update a local copy of the PR:
$ git checkout pull/576
$ git pull https://git.openjdk.org/jmc.git pull/576/head

Using Skara CLI tools

Checkout this PR locally:
$ git pr checkout 576

View PR using the GUI difftool:
$ git pr show -t 576

Using diff file

Download this PR as a diff file:
https://git.openjdk.org/jmc/pull/576.diff