chore: make version be added via premake option

tools/scripts/options.lua

@@ -1,3 +1,9 @@
+newoption {
+    trigger = "oat-version",
+    description = "Set the OAT version being compiled.",
+    value = "VERSION",
+    default = "_" -- An empty string is not recognized as a default
+}
 newoption {
     trigger = "debug-structureddatadef",
     description = "Activate additional debugging logic for StructuredDataDef assets"

tools/scripts/version.lua

@@ -2,13 +2,17 @@ local BuildSubFolderFolder = "premake"
 local HeaderFileName = "GitVersion.h"
 
 function GetGitVersion()
+    if _OPTIONS["oat-version"] ~= "_" then
+        return _OPTIONS["oat-version"]
+    end
+
     result, errorCode = os.outputof("git describe --tags")
 
     if errorCode == 0 then
         return result
     end
 
-    return "Unknown"
+    return "dev"
 end
 
 function GetVersionHeaderFolder()