🚧 Add bundledLambdas option for bundling them with esbuild

[iiroj]

This PR adds a new inputs.build.bundledLambdas option:

Name	Type	Default Value	Description
build.bundledLambdas	boolean	false	Experimental Set this to true to use esbuild to minify and bundle your Lambdas into a single file. This greatly decreases the Lambda file size and speeds up cold-boot time.

[codecov]

Codecov Report

Merging #2178 (c89413a) into master (5a33a65) will decrease coverage by 0.90%.
The diff coverage is 29.03%.

@@            Coverage Diff             @@
##           master    #2178      +/-   ##
==========================================
- Coverage   83.51%   82.60%   -0.91%     
==========================================
  Files         102      103       +1     
  Lines        3669     3725      +56     
  Branches     1166     1190      +24     
==========================================
+ Hits         3064     3077      +13     
- Misses        593      636      +43     
  Partials       12       12              

Impacted Files	Coverage Δ
...ckages/libs/lambda-at-edge/src/lib/bundleLambda.ts	9.09% <9.09%> (ø)
packages/libs/lambda-at-edge/src/build.ts	91.57% <40.90%> (-4.51%)	⬇️
...rless-components/nextjs-component/src/component.ts	86.20% <83.33%> (-0.16%)	⬇️
...ages/libs/core/src/build/lib/readDirectoryFiles.ts	100.00% <100.00%> (ø)
packages/libs/core/src/images/imageOptimizer.ts	80.17% <0.00%> (+0.44%)	⬆️

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[iiroj]

What do you think about this, @dphang? I didn't write any unit tests yet because I wanted to get some input first on the idea itself.

[dphang]

Seems promising, but hm, does this fully work with the serverless target? I thought one problem was the generated server-side chunks are dynamically imported by the corresponding pages and I think esbuild can't handle those properly?

[iiroj]

Thanks @dphang, I will investigate. If it doesn't work we need to keep the chunks around.

[iiroj]

@dphang you seem to be correct, and building the integration test directories with chunks does imply the bundled Lambda would be broken. This is relevant: evanw/esbuild#1155.

Let me close this PR for now...