Xmlkv should have all parameters as optional

[51-code]

Describe the bug

The following query:
index=abc | xmlkv

Results to the error:

java.lang.IllegalStateException: Parser failure on line 2, column 18 due to missing {GET_FIELD_SINGLE_QUOTED, GET_FIELD_DOUBLE_QUOTED, GET_FIELD_STRING} at 'maxinputs='
Please check that the query is written correctly. Otherwise, please report this error and include the query used and this error.

Also when giving just one of the parameters it will complain not receiving the other:
index=abc | xmlkv _raw

java.lang.IllegalStateException: Parser failure on line 2, column 22 due to mismatched input '<EOF>' expecting COMMAND_XMLKV_MODE_MAXINPUTS
Please check that the query is written correctly. Otherwise, please report this error and include the query used and this error.

Expected behavior

Both the field and the maxinputs parameters should be optional.

How to reproduce

Run the queries above.

Screenshots

Software version

5.11.0

Desktop (please complete the following information if relevant):

• OS:
• Browser:
• Version:

Additional context