feat(nextjs-cdk-construct): Allow cache policies to be provided as props

[jadenv]

Our company has started to extensively use the CDK construct for next.js and it's been working great so far 🎉

However, since each app builds its own 3 unique cache policies, we have started to run into a limitation. AWS only allows you to have 20 cache policies per account. See Cache policies per AWS account in AWS docs here:
https://docs.aws.amazon.com/AmazonCloudFront/latest/DeveloperGuide/cloudfront-limits.html#limits-policies

Since all the next apps have the same 3 cache policies duplicated, we created 3 universal ones to share across all our apps. Then, we will simply import the shared 3 policies into our next apps.

EX:

nextStaticsCachePolicy: CachePolicy.fromCachePolicyId(
      scope,
      'NextImageCache',
      'unique-cache-policy-id-here'
    )

This PR allows you to pass those policies into the construct so it will not make another 3 unique ones so you should be able to have as many next.js apps as you want in one account using this method!

[slsnextbot]

Handler Size Report

No changes to handler sizes.

Base Handler Sizes (kB) (commit ecb03a6)

{
    "Lambda": {
        "Default Lambda": {
            "Standard": 1524,
            "Minified": 668
        },
        "Image Lambda": {
            "Standard": 1488,
            "Minified": 800
        }
    },
    "Lambda@Edge": {
        "Default Lambda": {
            "Standard": 1534,
            "Minified": 673
        },
        "Default Lambda V2": {
            "Standard": 1526,
            "Minified": 670
        },
        "API Lambda": {
            "Standard": 634,
            "Minified": 318
        },
        "Image Lambda": {
            "Standard": 1496,
            "Minified": 805
        },
        "Regeneration Lambda": {
            "Standard": 1187,
            "Minified": 546
        },
        "Regeneration Lambda V2": {
            "Standard": 1253,
            "Minified": 573
        }
    }
}

New Handler Sizes (kB) (commit 000d0ef)

{
    "Lambda": {
        "Default Lambda": {
            "Standard": 1524,
            "Minified": 668
        },
        "Image Lambda": {
            "Standard": 1488,
            "Minified": 800
        }
    },
    "Lambda@Edge": {
        "Default Lambda": {
            "Standard": 1534,
            "Minified": 673
        },
        "Default Lambda V2": {
            "Standard": 1526,
            "Minified": 670
        },
        "API Lambda": {
            "Standard": 634,
            "Minified": 318
        },
        "Image Lambda": {
            "Standard": 1496,
            "Minified": 805
        },
        "Regeneration Lambda": {
            "Standard": 1187,
            "Minified": 546
        },
        "Regeneration Lambda V2": {
            "Standard": 1253,
            "Minified": 573
        }
    }
}

[codecov]

Codecov Report

Merging #2350 (000d0ef) into master (ecb03a6) will increase coverage by 0.02%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #2350      +/-   ##
==========================================
+ Coverage   83.55%   83.58%   +0.02%     
==========================================
  Files         102      102              
  Lines        3679     3685       +6     
  Branches     1176     1182       +6     
==========================================
+ Hits         3074     3080       +6     
  Misses        593      593              
  Partials       12       12              

Impacted Files	Coverage Δ
...rless-components/nextjs-cdk-construct/src/index.ts	93.91% <100.00%> (+0.33%)	⬆️

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