TERRA-113 ⁃ Add support for creating streaming functions

[SpencerC]

Being able to update functions as part of a CI workflow would be extremely powerful.

resource "astra_streaming_function" "streaming_function-1" {
  namespace     = "default"
  name               = "function-1"
  path_to_code = "../code"
  ...
}

┆Issue is synchronized with this Jira Task by Unito
┆Issue Number: TERRA-113
┆Priority: Major