fix(core): Convert group & pool names in SpotEventPluginFleet to lowercase

[kozlove-aws]

Problem

Groups & pools are always lowercase in Deadline.
The SpotEventPluginFleet is passing the Group/Pool names through as given, without ensuring that they are in lower case. With the SpotEventPluginFleet currently not creating the required groups, this means that it is impossible for a customer to create the required group on their own if they ask for one that has uppercase characters in it.

Solution

• Convert group and pool names lo lowercase
• Changed validation for group names

Testing

• Deployed farm with group and pool that names contain capital symbols.
• Verified that spot configuration deployed with converted group name.
• Created pool and group with lowercase names and send a job with this pool and group.
• Make sure that worker was spawned and rendered this job.

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By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license

[jericht]

Just one tiny comment otherwise this looks great!