Optimize ReadMe and run-webkit-app usage

https://bugs.webkit.org/show_bug.cgi?id=278906

Reviewed by Jonathan Bedard.

Add the guide of running applications in iOS simulator to ReadMe.
Update the utility `run-webkit-app` usage output.

* ReadMe.md:
* Tools/Scripts/webkitdirs.pm:
(determineXcodeSDKPlatformName):
(printHelpAndExitForRunAndDebugWebKitAppIfNeeded):

Canonical link: https://commits.webkit.org/285197@main

Author: Pancf

Diff for: ReadMe.md

@@ -142,6 +142,16 @@ run-safari --debug --ios-simulator
 
 In both cases, if you have built release builds instead, use `--release` instead of `--debug`.
 
+To run other applications, for example MobileMiniBrowser, with your local build of WebKit, run the following command:
+
+``` shell
+Tools/Scripts/run-webkit-app --debug --iphone-simulator <application-path>
+```
+
+#### Using Xcode
+
+Open `WebKit.xcworkspace`, select intended scheme such as MobileMiniBrowser and an iOS simulator as target, click run.
+
 ### Linux Ports
 
 If you have a development build, you can use the `run-minibrowser` script, e.g.:

Diff for: Tools/Scripts/webkitdirs.pm

@@ -984,9 +984,11 @@ sub determineXcodeSDKPlatformName {
         $xcodeSDKPlatformNameExplanation ||= "via argument, `--simulator`";
         $simulatorIdiom = 'iPhone';
     }
-    if (checkForArgumentAndRemoveFromARGV("--ios-simulator")) {
+    if (checkForArgumentAndRemoveFromARGV("--iphone-simulator") ||
+        checkForArgumentAndRemoveFromARGV("--ios-simulator")) {
+        # `--ios-simulator` option checking is for compatible here.
         $xcodeSDKPlatformName ||= 'iphonesimulator';
-        $xcodeSDKPlatformNameExplanation ||= "via argument, `--ios-simulator`";
+        $xcodeSDKPlatformNameExplanation ||= "via argument, `--iphone-simulator`";
         $simulatorIdiom = 'iPhone';
     }
     if (checkForArgumentAndRemoveFromARGV("--ipad-simulator")) {
@@ -2999,9 +3001,10 @@ sub printHelpAndExitForRunAndDebugWebKitAppIfNeeded
     return unless checkForArgumentAndRemoveFromARGV("--help");
 
     print STDERR <<EOF;
-Usage: @{[basename($0)]} [options] [args ...]
+Usage: @{[basename($0)]} [options] <application-path>
   --help                            Show this help message
   --no-saved-state                  Launch the application without state restoration
+  --debug|release                   build configuration
 
 Options specific to macOS:
   -g|--guard-malloc                 Enable Guard Malloc