Part of CBL 5579 in order to facilitate VS on .NET Android (#1993)

Cherry picked from d1d375b

This probably affects Java Android as well, but at least on lower API levels a native library without the lib prefix will not be automatically extracted in legacy packaging.  So Android needs to look for libCouchbaseLiteVectorSearch while others continue looking for CouchbaseLiteVectorSearch.  In the meantime added more logging to show details about the loading process.

LiteCore/Storage/SQLiteDataFile.cc

@@ -192,7 +192,12 @@ namespace litecore {
     // for more extensions.
     static void LoadVectorSearchExtension(sqlite3* sqlite) {
 #ifdef COUCHBASE_ENTERPRISE
+#    if defined(__ANDROID__)
+        static const char* extensionName = "libCouchbaseLiteVectorSearch";
+#    else
         static const char* extensionName = "CouchbaseLiteVectorSearch";
+#    endif
+
         if ( sExtensionPath.empty() ) return;
 
         // First enable extension loading (for security reasons it's off by default):

LiteCore/Support/Extension.cc

@@ -48,7 +48,10 @@ static string name_from_path(const string& extensionPath) {
     auto lastSlash = extensionPath.rfind(FilePath::kSeparator);
     if ( lastSlash == string::npos ) { return ""; }
 
-    return extensionPath.substr(lastSlash + 1);
+    auto raw_name = extensionPath.substr(lastSlash + 1);
+    if ( raw_name.substr(0, 3) == "lib" ) { return raw_name.substr(3); }
+
+    return raw_name;
 }
 
 static HMODULE try_open_lib(const string& extensionPath) {
@@ -63,11 +66,17 @@ static HMODULE try_open_lib(const string& extensionPath) {
     static constexpr const char* file_extension = ".so";
 #endif
 
+    LogToAt(DBLog, Info, "Looking for extension at %s...", extensionPath.c_str());
     HMODULE libHandle = cbl_dlopen(extensionPath.c_str());
-    if ( libHandle ) { return libHandle; }
+    if ( libHandle ) {
+        LogToAt(DBLog, Info, "\t...Found!");
+        return libHandle;
+    }
 
     string with_extension = extensionPath + file_extension;
-    libHandle             = cbl_dlopen(with_extension.c_str());
+    LogToAt(DBLog, Info, "Looking for extension at %s", with_extension.c_str());
+    libHandle = cbl_dlopen(with_extension.c_str());
+    if ( libHandle ) { LogToAt(DBLog, Info, "\t...Found!"); }
 
 #ifdef WIN32
     if ( libHandle ) {