Support more orderless parameters for KEMANS and AD commands

[jackiehanyang]

Is your feature request related to a problem? Please describe.
Currently the KMEANS command works in this format (version 1.3):
{ "query": "source=xxx | fields xxx | kmeans 2"}

We can improve it by allowing more parameters and define a name to each parameter so parameters can be orderless. For example, the previous command now works in this format:
{ "query": "source=xxx | fields xxx | kmeans centroids=2"}

Describe the solution you'd like
Changing the Antlr parsing tree so it can takes more orderless parameters.

Describe alternatives you've considered
A clear and concise description of any alternative solutions or features you've considered.

Additional context
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