fixes: #943 give access to underlying resources and enable custom s3 props

[kirkness]

It's quite often the case that you need to access the underlying resources, for example, to update their roles or to read their configuration to pass into another resource. This PR exposes all created resources as properties on the construct. It also allows users to pass in custom S3 configuration.

[codecov]

Codecov Report

Merging #955 (06403b8) into master (650f8ac) will increase coverage by 0.00%.
The diff coverage is 87.50%.

❗ Current head 06403b8 differs from pull request most recent head 7f93288. Consider uploading reports for the commit 7f93288 to get more accurate results

@@           Coverage Diff           @@
##           master     #955   +/-   ##
=======================================
  Coverage   81.39%   81.40%           
=======================================
  Files          69       69           
  Lines        2516     2517    +1     
  Branches      599      600    +1     
=======================================
+ Hits         2048     2049    +1     
  Misses        401      401           
  Partials       67       67           

Impacted Files	Coverage Δ
...rless-components/nextjs-cdk-construct/src/index.ts	94.33% <87.50%> (+0.10%)	⬆️

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[dphang]

LGTM!