Provide short term solution for array "star" substitution

[skaegi]

We want to eventually just use JSONPath for variable expansion but in the short-term we should just add an extra star expansion for array types for our string-prefix based expansion. e.g. params.myarray will cause the create "both" a params.myarray and params.myarray[*] map key for ApplyArrayReplacements and the various validate methods.

This will let us update our tests to use the star-expansion in advance of jsonpath support.

[skaegi]

/assign

[dibyom]

/kind feature