Execute command in the command shell and return a promise for {code, output, error} (the exit code, the stdout output and the stderr output).

• If the opts.input string has been assigned then it is piped to the shell stdin.
• opts.cwd sets the shell current working directory (defaults to the parent process working directory).
• The opts.env mapping passes additional environment variables to the shell.
• opts.stdout and opts.stderr have Deno.CommandOptions.stdout and Deno.CommandOptions.stdout semantics respectively.
• opts.stdout defaults to "piped". opts.stderr defaults to "inherit" (to capture stderr set opts.stderr to "piped").

Examples:

const { code, output } = await shCapture("echo Hello");
const { code, output, error } = await shCapture( "mkdir tmpdir", { stderr: "piped" });
const vers = (await shCapture("make version")).output.trim();