Iss2409 - Remove Java 11 support

[jadecarino]

Why?

For galasa-dev/projectmanagement#2409

Changes

• Maven compiler source and target updated to Java 17
• Build Simplatform jar (not currently used) from base image of OpenJDK 17
• Simbank's Web App docker image builds from base image Tomcat 9 (must stay below Tomcat 10 or need to update to the Jakarta API instead of Javax) with JRE 17
• I've tested these changes as much as I can: build is successful, all Simbank tests ran successfully, can connect to the Simbank application from a 3270 emulator, Web App deploys successfully with new Tomcat server, and WebAppIntegrationTest passes with Selenium driving a browser.