Make JTSConfig load lazy

[pomadchin]

Overview

This PR fixes the JTS config loading ordering. That could cause bad JTS factories init, since sometimes the reference.conf file could be loaded into memory after the call to the config. That could cause following errors:

Caused by: pureconfig.error.ConfigReaderException: Cannot convert configuration to a geotrellis.vector.conf.JtsConfig. Failures are:
  at the root:
    - (merge of system properties,reference.conf @ jar:file:/.../sbt/1.4.9/ssl-config-core_2.12-0.4.0.jar!/reference.conf: 1) Key not found: 'geotrellis'.

For the context: this could only happen in runs through SBT.
I did a little bit of tracing down the history of this bug and it turned out that it appeared in 1.4.0 and all 1.4.x versions are affected. However, in 1.5.x (checked with RC2) this issue is gone.

Checklist

• ./CHANGELOG.md updated, if necessary. Link to the issue if closed, otherwise the PR.

[jisantuc]

Tested with local publication in the setting that produced the bug, eeverything's great 🎉