Enable fgviewer for android remote debugging (#8483)

* Enable fgviewer for the users

* Fix incorrect position

* Update

* Support remote debug server

* Enable fgviewer on android

* Link and include fgviewer_resources

* Adjust js to show untitled view

libs/fgviewer/src/DebugServer.cpp

@@ -30,9 +30,26 @@
 
 namespace filament::fgviewer {
 
+// If set to 0, this serves HTML from a resgen resource. Use 1 only during local development, which
+// serves files directly from the source code tree.
+#define SERVE_FROM_SOURCE_TREE 0
+
+#if SERVE_FROM_SOURCE_TREE
 namespace {
 std::string const BASE_URL = "libs/fgviewer/web";
 } // anonymous
+#else
+#include "fgviewer_resources.h"
+#include <unordered_map>
+
+namespace {
+struct Asset {
+    std::string_view mime;
+    std::string_view data;
+};
+std::unordered_map<std::string_view, Asset> ASSET_MAP;
+} // anonymous
+#endif // SERVE_FROM_SOURCE_TREE
 
 using namespace utils;
 
@@ -56,10 +73,21 @@ public:
             uri = "/index.html";
         }
 
+#if SERVE_FROM_SOURCE_TREE
         if (uri == "/index.html" || uri == "/app.js" || uri == "/api.js") {
             mg_send_file(conn, (BASE_URL + uri).c_str());
             return true;
         }
+#else
+        auto const& asset_itr = ASSET_MAP.find(uri);
+        if (asset_itr != ASSET_MAP.end()) {
+            auto const& mime = asset_itr->second.mime;
+            auto const& data = asset_itr->second.data;
+            mg_printf(conn, kSuccessHeader.data(), mime.data());
+            mg_write(conn, data.data(), data.size());
+            return true;
+        }
+#endif
         slog.e << "[fgviewer] DebugServer: bad request at line " <<  __LINE__ << ": " << uri << io::endl;
         return false;
     }
@@ -68,6 +96,21 @@ private:
 };
 
 DebugServer::DebugServer(int port) {
+#if !SERVE_FROM_SOURCE_TREE
+    ASSET_MAP["/index.html"] = {
+        .mime = "text/html",
+        .data = {(char const*) FGVIEWER_RESOURCES_INDEX_DATA},
+    };
+    ASSET_MAP["/app.js"] = {
+        .mime = "text/javascript",
+        .data = {(char const*) FGVIEWER_RESOURCES_APP_DATA},
+    };
+    ASSET_MAP["/api.js"] = {
+        .mime = "text/javascript",
+        .data = {(char const*) FGVIEWER_RESOURCES_API_DATA},
+    };
+#endif
+
     // By default the server spawns 50 threads so we override this to 10. According to the civetweb
     // documentation, "it is recommended to use num_threads of at least 5, since browsers often
     /// establish multiple connections to load a single web page, including all linked documents