Make it possible to use the detected properties before reading pom.xml

[nikolaybespalov]

Hi, Currently, it is not possible to use the detected properties to activate profiles.

PR implements afterSessionStart in addition to afterProjectsRead. This makes it possible to use the detected properties to activate profiles.

...
<profile>
  <id>Ubuntu</id>
  <activation>
    <property>
      <name>os.detected.release</name>
      <value>ubuntu</value>
    </property>
  </activation>
...
  <!-- Now you can do Ubuntu-specific work -->
...
</profile>

It would be great if this functionality was available in the extension.

Also added integration test that checks whether the profile can be activated by detected properties

[nikolaybespalov]

I did it

[nikolaybespalov]

Great! Thanks a lot!