Add some env variables to control Olympus behavior

Mainly for use by the Nix package, but could probably come in handy for other packages as well.

sharp/CmdInstallEverest.MiniInstaller.cs

@@ -206,6 +206,8 @@ private void BootNative(MiniInstallerBridge bridge) {
                     RedirectStandardError = true,
                     CreateNoWindow = true,
                 }}) {
+                    proc.HandleLaunchWrapper("MINIINSTALLER");
+
                     proc.OutputDataReceived += (o, e) => bridge.WriteLine(e.Data);
                     proc.ErrorDataReceived += (o, e) => bridge.WriteLine(e.Data);
 

sharp/CmdLaunch.cs

@@ -74,6 +74,8 @@ public override string Run(string root, string args, bool force) {
             if (!string.IsNullOrEmpty(args))
                 game.StartInfo.Arguments = args;
 
+            game.HandleLaunchWrapper("CELESTE");
+
             // Flatpak detection
             // or string.Equals(Environment.GetEnvironmentVariable("container"), "flatpak");
             if (File.Exists("/.flatpak-info")) {

sharp/CmdLaunchLoenn.cs

@@ -31,6 +31,7 @@ public override string Run(string root) {
 
             Console.Error.WriteLine($"Starting Loenn process: {loenn.StartInfo.FileName} {loenn.StartInfo.Arguments} (in {root})");
 
+            loenn.HandleLaunchWrapper("LOENN");
             loenn.Start();
             return null;
         }

sharp/Extensions.cs

@@ -3,6 +3,7 @@
 using System.IO;
 using System.Linq;
 using System.Text;
+using System.Diagnostics;
 using System.Threading.Tasks;
 using YamlDotNet.Serialization;
 using YamlDotNet.Serialization.ObjectFactories;
@@ -17,5 +18,14 @@ public static bool ReadLineUntil(this TextReader reader, string wanted) {
             return false;
         }
 
+        public static void HandleLaunchWrapper(this Process proc, string wrapperName) {
+            // Handle launch wrappers
+            string wrapper = Environment.GetEnvironmentVariable($"OLYMPUS_{wrapperName}_WRAPPER");
+            if (!string.IsNullOrEmpty(wrapper)) {
+                proc.StartInfo.Arguments = $"{proc.StartInfo.FileName} {proc.StartInfo.Arguments}";
+                proc.StartInfo.FileName = wrapper;
+            }
+        }
+
     }
 }

src/modinstaller.lua

@@ -41,7 +41,7 @@ function modinstaller.register()
         return false
 
     elseif userOS == "Linux" then
-        if fs.isFile("/.flatpak-info") then
+        if fs.isFile("/.flatpak-info") or os.getEnv("OLYMPUS_SKIP_SCHEME_HANDLER_CHECK") == "1" then
             return false
         end