loveplus: improve window searching for touch hook (#321)

## Link to GitHub Issue, if one exists
Fixes #320 

## Description of change
Replacing the existing logic that searches for game window to hook touch
on.

Eventually, we should fix all the other games that hook touch by
matching on window title with a call to `FindProcessWindowBeginsWith`.

## Testing
Tested with notepad open that was also titled `LovePlusAC`. Game hooked
correctly when the game was in focus during boot, and also when notepad
was in focus.

src/spice2x/util/utils.h

@@ -227,6 +227,7 @@ static inline std::vector<HWND> find_windows_beginning_with(const std::string &t
     return windows;
 }
 
+// exists for compat only; prefer to use FindProcessWindowBeginsWith instead
 static inline HWND FindWindowBeginsWith(std::string title) {
 
     // get all windows
@@ -248,6 +249,28 @@ static inline HWND FindWindowBeginsWith(std::string title) {
     return nullptr;
 }
 
+static inline HWND FindProcessWindowBeginsWith(const std::string &title) {
+    // try foreground window first
+    HWND fg_win = GetForegroundWindow();
+    if (string_begins_with(get_window_title(fg_win), title)) {
+        DWORD fg_pid;
+        GetWindowThreadProcessId(fg_win, &fg_pid);
+        if (fg_pid == GetCurrentProcessId()) {
+            return fg_win;
+        }
+    }
+
+    // try different windows
+    for (const auto window : find_windows_beginning_with(title)) {
+        DWORD fg_pid;
+        GetWindowThreadProcessId(window, &fg_pid);
+        if (fg_pid == GetCurrentProcessId()) {
+            return window;
+        }
+    }
+    return nullptr;
+}
+
 static inline std::string get_last_error_string() {
 
     // get error