Warn about flipped $ and " in $"(cmd)" (fixes #1517)

CHANGELOG.md

@@ -3,6 +3,7 @@
 - Preliminary support for fix suggestions
 - Files containing Bats tests can now be checked
 - Directory wide directives can now be placed in a `.shellcheckrc`
+- SC2247: Warn about $"(cmd)" and $"{var}"
 - SC2246: Warn if a shebang's interpreter ends with /
 - SC2245: Warn that Ksh ignores all but the first glob result in `[`
 - SC2243/SC2244: Suggest using explicit -n for `[ $foo ]`