Add intrinsic support for Serverless::Function.DeploymentPreference.Enabled

[eddiecho]

Add intrinsic support for Serverless::Function.DeploymentPreference.Enabled

Issue #, if available:

Description of changes:
Added intrinsics for Serverless::Function.DeploymentPreferences.Enabled. It now supports Fn::If, Fn::FindInMap, !Ref, etc.

Description of how you validated changes:
Wrote/updated unit tests validating the changes. Tested changes with a production template to verify changes manually.

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

Merging #1196 into master will decrease coverage by 0.14%.
The diff coverage is 64.7%.

@@            Coverage Diff             @@
##           master    #1196      +/-   ##
==========================================
- Coverage   94.36%   94.22%   -0.15%     
==========================================
  Files          71       71              
  Lines        3621     3635      +14     
  Branches      713      717       +4     
==========================================
+ Hits         3417     3425       +8     
- Misses        104      108       +4     
- Partials      100      102       +2

Impacted Files	Coverage Δ
samtranslator/translator/arn_generator.py	76.92% <0%> (-10.04%)	⬇️
samtranslator/model/sam_resources.py	95.51% <100%> (+0.01%)	⬆️
samtranslator/sdk/parameter.py	88% <70%> (-12%)	⬇️

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[ShreyaGangishetty]

@eddiecho Thank you for contributing this! This looks good to me