Adds data models for Rollup and tests

[dbbaughe]

Issue #, if available:

Description of changes:
Adds data models for Rollup and tests
Also refactors some util methods into higher level package

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

[codecov]

Codecov Report

Merging #319 (e51cdef) into master (9423fbb) will decrease coverage by 2.66%.
The diff coverage is 59.49%.

@@             Coverage Diff              @@
##             master     #319      +/-   ##
============================================
- Coverage     76.15%   73.48%   -2.67%     
- Complexity      875     1012     +137     
============================================
  Files           123      139      +16     
  Lines          4538     5277     +739     
  Branches        677      826     +149     
============================================
+ Hits           3456     3878     +422     
- Misses          710      970     +260     
- Partials        372      429      +57     

Impacted Files	Coverage Δ	Complexity Δ
...agement/indexstatemanagement/ManagedIndexRunner.kt	55.65% <ø> (ø)	41.00 <0.00> (ø)
...dexstatemanagement/elasticapi/ElasticExtensions.kt	65.11% <ø> (+3.57%)	0.00 <0.00> (ø)
...t/indexstatemanagement/model/ManagedIndexConfig.kt	78.50% <ø> (ø)	18.00 <0.00> (ø)
...dexmanagement/indexstatemanagement/model/Policy.kt	90.21% <ø> (ø)	21.00 <0.00> (ø)
...nt/indexstatemanagement/model/destination/Chime.kt	54.54% <ø> (+13.63%)	4.00 <0.00> (+2.00)
...nt/indexstatemanagement/model/destination/Slack.kt	40.90% <ø> (ø)	2.00 <0.00> (ø)
...ent/indexstatemanagement/util/ManagedIndexUtils.kt	78.23% <ø> (ø)	87.00 <0.00> (ø)
...ment/indexstatemanagement/util/RestHandlerUtils.kt	100.00% <ø> (ø)	0.00 <0.00> (ø)
...orelasticsearch/indexmanagement/util/IndexUtils.kt	76.92% <ø> (ø)	1.00 <0.00> (ø)
...rch/indexmanagement/rollup/model/RollupMetadata.kt	26.19% <26.19%> (ø)	3.00 <3.00> (?)
... and 37 more

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 9423fbb...e51cdef. Read the comment docs.

[dbbaughe]

There are some tests missing that will come in later PRs as we break the feature branch apart that cover the missing methods in here.