feat: Security Policy for Listener in Application load balancer

[KollaAdithya]

This PR resolves #1342
AWS Load Balancer listeners can restrict the tls protocol versions clients use to connect through an sslpolicy. The default policy allows for insecure protocol versions for compatibility.
For those with stricter security goals it would be great to expose the ability to only accept current tls protocol versions.

This security policy for a HTTPS listener helps to negotiate SSL connections between a client and the load balancer.

For Example if Environment manifest contains,

In case of Public Application load balancer

http:
  public: 
    certificates:
      - arn:aws:acm: ${AWS_REGION}:${AWS_ACCOUNT_ID}:certificate/13245665-cv8f-adf3-j7gd-adf876af95
    ssl_policy: ELBSecurityPolicy-FS-1-1-2019-08

In case of Internal load balancer

http:
 private: 
    certificates:
      - arn:aws:acm: ${AWS_REGION}:${AWS_ACCOUNT_ID}:certificate/13245665-cv8f-adf3-j7gd-adf876af95
    ssl_policy: ELBSecurityPolicy-FS-1-1-2019-08

By Default ELBSecurityPolicy-2016-08 will be set for a https listener in a public application load balancer and internal load balancer. You can access the available security policies at https://docs.aws.amazon.com/elasticloadbalancing/latest/application/create-https-listener.html#describe-ssl-policies

By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the Apache 2.0 License.

[codecov-commenter]

Codecov Report

Merging #4099 (012a0e4) into mainline (112d9af) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@            Coverage Diff            @@
##           mainline    #4099   +/-   ##
=========================================
  Coverage     69.13%   69.14%           
=========================================
  Files           249      249           
  Lines         35656    35662    +6     
  Branches        264      264           
=========================================
+ Hits          24652    24658    +6     
  Misses         9808     9808           
  Partials       1196     1196           

Impacted Files	Coverage Δ
internal/pkg/template/env.go	49.23% <ø> (ø)
internal/pkg/deploy/cloudformation/stack/env.go	72.52% <100.00%> (+0.47%)	⬆️
internal/pkg/manifest/env.go	77.77% <100.00%> (ø)

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[paragbhingre]

Overall looks great, just few nits.

[huanjani]

Looks good! 😻 Just a few changes, please, then feel free to remove the do-not-merge label! Thank you!