rust-chg: reimplement run_command operation as async function
The crafted state machine is no longer needed thanks to async/await.
The state machine is basically rewritten as follows:
- Ready(..) -> return ..
- PollAgain(..) -> run .. and await
- Err(..) -> return Err(..)
Differential Revision: https://phab.mercurial-scm.org/D8445
BasedOnStyle: LLVM
IndentWidth: 8
UseTab: ForIndentation
BreakBeforeBraces: Linux
AllowShortIfStatementsOnASingleLine: false
IndentCaseLabels: false
AllowShortBlocksOnASingleLine: false
AllowShortFunctionsOnASingleLine: false
IncludeCategories:
- Regex: '^<'
Priority: 1
- Regex: '^"'
Priority: 2