permit install into windows program files

when installing terasology into program files, that dir is not writeable.
starting up, terasology tries to create a folder in .local, which then
fails.

therefor, permit to start the application from a different directory,
and let it anyway find its libraries via the classpath. a workaround,
as the app should ideally know its location and other jarfiles without
tinkering with the classpath.

Co-authored-by: BenjaminAmos <24301287+BenjaminAmos@users.noreply.github.com>

facades/PC/src/main/startScripts/windowsStartScript.bat.gsp

@@ -63,7 +63,7 @@ goto fail
 <% if ( mainClassName.startsWith('--module ') ) { %>set MODULE_PATH=$modulePath<% } %>
 
 @rem Execute ${applicationName}
-"%JAVA_EXE%" %DEFAULT_JVM_OPTS% %JAVA_OPTS% %${optsEnvironmentVar}% <% if ( appNameSystemProperty ) { %>"-D${appNameSystemProperty}=%APP_BASE_NAME%"<% } %> <% if ( mainClassName.startsWith('--module ') ) { %>--module-path "%MODULE_PATH%" <% } %>-jar lib\\Terasology.jar %*
+"%JAVA_EXE%" %DEFAULT_JVM_OPTS% %JAVA_OPTS% %${optsEnvironmentVar}% <% if ( appNameSystemProperty ) { %>"-D${appNameSystemProperty}=%APP_BASE_NAME%"<% } %> <% if ( mainClassName.startsWith('--module ') ) { %>--module-path "%MODULE_PATH%" <% } %>-jar "%APP_HOME%\\lib\\Terasology.jar" %*
 
 :end
 @rem End local scope for the variables with windows NT shell