Repeat argument fixes

[camargo]

We need to:

1. Remove the nested repeat argument since it's not supported in the AMPCS command dictionary spec:
   

   seq-json-schema/schema.json

   Line 445 in b56782b

   "$ref": "#/$defs/repeat_argument"

2. Make the repeat arg an array of arrays so we can actually repeat the arguments.
   

   seq-json-schema/schema.json

   Line 424 in b56782b

   "value": {

We should add tests that cover both of these changes.