[Feature Request] Support highlighting of Move snippets outside of modules and scripts

[gregnazario]

I noticed that when you do not have a full module in a block it doesn't highlight correctly.

Example:

module 0x42::example {
  fun do_something() {
    5+5
  }
}

vs

script {
  fun main() {
    5+5
  }
}

vs

fun do_something() {
  5+5
}