GP-5179: Improvements to pyghidra_launcher.py

* Specifying supported Python versions in application.properties
so other things can get access to it (similar to how we do it for Java
and Gradle supported versions)

* Only try to launch PyGhidra with a supported version of Python

gradle/hasPythonPackage.gradle

@@ -49,7 +49,7 @@ task buildPyPackage {
 
 	doLast {
 		if (rootProject.PYTHON3 == null) {
-			throw new GradleException("A supported version of Python ${SUPPORTED_PY_VERSIONS} was not found!")
+			throw new GradleException("A supported version of Python [${PYTHON_SUPPORTED}] was not found!")
 		}
 	
 		File setuptools = project(":Debugger-rmi-trace").findPyDep(".")

gradle/root/distribution.gradle

@@ -271,7 +271,7 @@ task createGhidraStubsWheel {
 		File setuptools = project(":Debugger-rmi-trace").findPyDep(".")
 		
 		if (PYTHON3 == null) {
-			throw new GradleException("A supported version of Python ${SUPPORTED_PY_VERSIONS} was not found!")
+			throw new GradleException("A supported version of Python [${PYTHON_SUPPORTED}] was not found!")
 		}
 		
 		exec {

gradle/root/venv.gradle

@@ -27,7 +27,7 @@ task createPythonVirtualEnvironment(type: Exec) {
 	
 	doFirst {
 		if (rootProject.PYTHON3 == null) {
-			throw new GradleException("A supported version of Python ${SUPPORTED_PY_VERSIONS} was not found!")
+			throw new GradleException("A supported version of Python [${PYTHON_SUPPORTED}] was not found!")
 		}
 		
 		commandLine rootProject.PYTHON3

gradle/support/loadApplicationProperties.gradle

@@ -4,9 +4,9 @@
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
- * 
+ *
  *      http://www.apache.org/licenses/LICENSE-2.0
- * 
+ *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
@@ -28,6 +28,7 @@ file("Ghidra/application.properties").withReader { reader ->
 	project.ext.JAVA_COMPILER = ghidraProps.getProperty('application.java.compiler')
 	project.ext.GRADLE_MIN = ghidraProps.getProperty('application.gradle.min')
 	project.ext.GRADLE_MAX = ghidraProps.getProperty('application.gradle.max')
+	project.ext.PYTHON_SUPPORTED = ghidraProps.getProperty('application.python.supported')
 	project.ext.DISTRO_PREFIX = "ghidra_${version}_${RELEASE_NAME}"
 	
 	// Build dates may or may not be already present in the application.properties file.