graphics: submonitor refresh rate option (#507)

## Description of change
Add an option that forces requested refresh rate value for the second
monitor; i.e., instead of 60Hz allow the user to override the adapter to
be 70Hz.

Useful for people who have a touch screen that can't do 60Hz.

I don't know if this would cause any timing issues in IIDX or SDVX, but
it seems to boot and monitor check is unaffected.

## Testing
Tested TDJ And UFC mode with a submonitor that can only do 61Hz.

src/spice2x/launcher/options.cpp

@@ -221,9 +221,11 @@ static const std::vector<OptionDefinition> OPTION_DEFINITIONS = {
         .category = "Graphics (Full Screen)",
     },
     {
-        .title = "Force Refresh Rate",
+        .title = "Force Monitor Refresh Rate",
         .name = "graphics-force-refresh",
-        .desc = "Force the refresh rate for the primary display adapter; works in both full screen and windowed modes",
+        .desc =
+            "Attempt to change the refresh rate for the primary monitor before the game boots; "
+            "works in both full screen and windowed modes, but known to fail for some games",
         .type = OptionType::Integer,
         .category = "Graphics (Common)",
     },
@@ -254,6 +256,17 @@ static const std::vector<OptionDefinition> OPTION_DEFINITIONS = {
         .hidden = true,
         .category = "Graphics (Full Screen)"
     },
+    {
+        // FullscreenSubRefreshRate
+        .title = "Force Submonitor Refresh Rate (EXPERIMENTAL)",
+        .name = "graphics-force-refresh-sub",
+        .desc =
+            "Override fullscreen refresh rate requested by the game for second monitor, "
+            "useful if you have a sub monitor that is not quite exactly 60Hz.\n\n"
+            "WARNING: experimental as we have not done extensive testing to see if this causes desyncs",
+        .type = OptionType::Integer,
+        .category = "Graphics (Full Screen)"
+    },
     {
         // Graphics9On12
         .title = "DirectX 9 on 12 (DEPRECATED - use -dx9on12 instead)",