fix(policy-devel): inputs don't accept multiple values

[Piskoo]

This PR fixes issue with passing arrays in --input flag.

Example

By passing --input licenses=AGPL,GPL in the eval command values can now be accessed with input.args.licenses[0] and input.args.licenses[1] in the rego script.

Closes #2351

[migmartri]

mind explaining why the previous one didn't work? Thanks!

[Piskoo]

The issue was caused by how Cobra treats commas for StringSliceVar. Here Cobra does preprocessing where values are split with , into separate strings, where in StringArrayVar strings are kept as is.

[migmartri]

so in that case we should use String no? StringSliceVar allows us to do

--input foo=bar --input bar=baz

is what I wrote correct?

[Piskoo]

StringArrayVar also allows

--input foo=bar --input bar=baz

but also allows

--input foo=bar,baz

to be treated as multi value, but has a trade-off of not being able to declare

--input foo=bar,bar=baz

because currently that becomes

[]string{"foo=bar,bar", "baz"}

Both StringSliceVar and StringArrayVar have drawbacks that can be fixed with custom parsing logic

[migmartri]

right, but my question is, do we need multi input or regular strings are enough? I thought that we were asking to provide comma separated values and the engine was doing smth, I guess that not, that we want to have arrays.

[Piskoo]

We want multi input, the previous change related to commas was for escaping comma separated values, before there was no way to pass e.g.

with:
  foo: bar, baz

to get

"foo": "bar, baz"

now \, can be used to get that output. But in this case using StringArrayVar makes it so the input is preprocessed by Cobra before it is passed to engine