feat: add support for DefaultRouteSettings in HttpApi

[keetonian]

Issue #, if available:
#1451
Description of changes:
Add support for DefaultRouteSettings in HttpApi resources
Description of how you validated changes:

Checklist:

• Write/update tests
• make pr passes
• Update documentation
• Verify transformed template deploys and application functions as expected
• Add/update example to examples/2016-10-31

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

[codecov-io]

Codecov Report

❗ No coverage uploaded for pull request base (develop@0f26f6f). Click here to learn what that means.
The diff coverage is 100%.

@@            Coverage Diff            @@
##             develop   #1461   +/-   ##
=========================================
  Coverage           ?   94.4%           
=========================================
  Files              ?      78           
  Lines              ?    4716           
  Branches           ?     948           
=========================================
  Hits               ?    4452           
  Misses             ?     121           
  Partials           ?     143

Impacted Files	Coverage Δ
samtranslator/model/eventsources/push.py	90.78% <100%> (ø)
samtranslator/model/api/api_generator.py	95.07% <100%> (ø)
samtranslator/model/sam_resources.py	94.06% <100%> (ø)
samtranslator/open_api/open_api.py	93.87% <100%> (ø)
samtranslator/__init__.py	100% <100%> (ø)
samtranslator/model/api/http_api_generator.py	98.34% <100%> (ø)

---

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 0f26f6f...cb3a969. Read the comment docs.