actionify get policy API

[bowenlan-amzn]

Issue #, if available:
#292

Description of changes:
actionify get policy API, refactor our API code so we have an action name to each API

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 #307 into master will increase coverage by 0.13%.
The diff coverage is 91.01%.

@@             Coverage Diff              @@
##             master     #307      +/-   ##
============================================
+ Coverage     74.96%   75.09%   +0.13%     
- Complexity      829      850      +21     
============================================
  Files           116      120       +4     
  Lines          4442     4506      +64     
  Branches        670      674       +4     
============================================
+ Hits           3330     3384      +54     
- Misses          751      756       +5     
- Partials        361      366       +5     

Impacted Files	Coverage Δ	Complexity Δ
...ment/transport/action/getpolicy/GetPolicyAction.kt	66.66% <66.66%> (ø)	2.00 <2.00> (?)
...ent/transport/action/getpolicy/GetPolicyRequest.kt	80.95% <80.95%> (ø)	7.00 <7.00> (?)
...sport/action/getpolicy/TransportGetPolicyAction.kt	92.59% <92.59%> (ø)	3.00 <3.00> (?)
...nt/transport/action/getpolicy/GetPolicyResponse.kt	96.77% <96.77%> (ø)	10.00 <10.00> (?)
...ticsearch/indexmanagement/IndexManagementPlugin.kt	91.54% <100.00%> (+0.12%)	9.00 <0.00> (ø)
...statemanagement/resthandler/RestGetPolicyAction.kt	85.71% <100.00%> (-8.23%)	5.00 <0.00> (-1.00)
...nt/indexstatemanagement/model/destination/Chime.kt	40.90% <0.00%> (-13.64%)	2.00% <0.00%> (-2.00%)
...anagement/indexstatemanagement/model/Transition.kt	64.61% <0.00%> (-3.08%)	5.00% <0.00%> (ø%)
... and 3 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 c3342a6...d3b93c3. Read the comment docs.