Update dependencies and improve formatting of pom.xml

[Avery-Dunn]

This PR updates various dependencies used during tests to the latest version, as well as some small formatting improvements. Changes were only made to dependencies with the 'test' scope, should this should not affect production behavior in any way.

A few dependencies' latest version do not support Java 8, so these were only updated to the latest compatible version. Since newer major versions target later versions of Java, these dependencies are unlikely to receive updates going forward:

• org.mockito.mockito-inline and org.mockito.mockito-junit-jupiter
  • Used for mocking in unit tests
• org.seleniumhq.selenium
  • Used for browser interaction in integration tests

There were several vestigial dependencies which were no longer used due to various refactors and updates over the years:

• org.apache.httpcomponents.httpclient
  • Superseded by other HTTP helpers and our own implementations
• com.google.guava.guava
  • Various utilities which were no longer used
• ch.qos.logback.logback-classic
  • No longer necessary due to SLF4J dependencies

Finally, some new properties were added which can be set when running the mvn command, and allows us to skip either the unit or integration tests separately when running the mvn command locally or in the build pipelines.