Added "GET_QDN_RESOURCE_URL" Q-Apps action, to allow a website/app to programmatically determine the URL to retrieve any QDN resource it needs to access.

Examples:

### Get URL to load a QDN resource
```
let url = await qortalRequest({
    action: "GET_QDN_RESOURCE_URL",
    service: "THUMBNAIL",
    name: "QortalDemo",
    identifier: "qortal_avatar"
    // path: "filename.jpg" // optional - not needed if resource contains only one file
});
```

### Get URL to load a QDN website
```
let url = await qortalRequest({
    action: "GET_QDN_RESOURCE_URL",
    service: "WEBSITE",
    name: "QortalDemo",
});
```

### Get URL to load a specific file from a QDN website
```
let url = await qortalRequest({
    action: "GET_QDN_RESOURCE_URL",
    service: "WEBSITE",
    name: "AlphaX",
    path: "/assets/img/logo.png"
});
```

Q-Apps.md

@@ -77,6 +77,7 @@ Here is a list of currently supported actions:
 - FETCH_BLOCK_RANGE
 - SEARCH_TRANSACTIONS
 - GET_PRICE
+- GET_QDN_RESOURCE_URL
 - LINK_TO_QDN_RESOURCE
 
 More functionality will be added in the future.
@@ -404,6 +405,36 @@ let res = await qortalRequest({
 });
 ```
 
+### Get URL to load a QDN resource
+```
+let url = await qortalRequest({
+    action: "GET_QDN_RESOURCE_URL",
+    service: "THUMBNAIL",
+    name: "QortalDemo",
+    identifier: "qortal_avatar"
+    // path: "filename.jpg" // optional - not needed if resource contains only one file
+});
+```
+
+### Get URL to load a QDN website
+```
+let url = await qortalRequest({
+    action: "GET_QDN_RESOURCE_URL",
+    service: "WEBSITE",
+    name: "QortalDemo",
+});
+```
+
+### Get URL to load a specific file from a QDN website
+```
+let url = await qortalRequest({
+    action: "GET_QDN_RESOURCE_URL",
+    service: "WEBSITE",
+    name: "AlphaX",
+    path: "/assets/img/logo.png"
+});
+```
+
 ### Link/redirect to another QDN website
 Note: an alternate method is to include `<a href="qortal://WEBSITE/QortalDemo">link text</a>` within your HTML code.
 ```

src/main/resources/q-apps/q-apps.js

@@ -134,6 +134,10 @@ window.addEventListener("message", (event) => {
             response = httpGet("/names/" + data.name);
             break;
 
+        case "GET_QDN_RESOURCE_URL":
+            response = buildResourceUrl(data.service, data.name, data.identifier, data.path);
+            break;
+
         case "LINK_TO_QDN_RESOURCE":
             if (data.service == null) data.service = "WEBSITE"; // Default to WEBSITE
             window.location = buildResourceUrl(data.service, data.name, data.identifier, data.path);