Configure Maven toolchains in the Docker container

[olafurpg]

The docker container pre-installs Java 8/11/17 but the installations are not visible to Maven toolchains. We should update ~/.m2/toolchains.xml to point to the Java installations

❯ cat ~/.m2/toolchains.xml
<?xml version="1.0" encoding="UTF8"?>
<toolchains>
  <toolchain>
    <type>jdk</type>
    <provides>
      <version>17</version>
      <vendor>sun</vendor>
    </provides>
    <configuration>
       <jdkHome>/Users/olafurpg/Library/Caches/Coursier/jvm/[email protected]/Contents/Home</jdkHome>
    </configuration>
  </toolchain>
</toolchains>