Simplify the Webpack configuration

[JoshuaLicense]

Description

• Moves from a series of Webpack configuration files to a single Typescript version of the configuration (without losing any functionality).
• Reduces build times by half (~2000ms vs. ~1100ms). In MOTH, build times reduced from ~12s to ~8s.
• Dynamically retrieves the Lambda names rather than being hardcoded. No manual Webpack changes are required if a new Lambda is added.
• Production builds now zip all Lambda functions rather than just a single one.

Requires: https://github.com/dvsa/dvsa-lambda-starter/pull/63 to be merged.

Type of change

• [ ] Bug fix (non-breaking change which fixes an issue)
• [ ] Feature (non-breaking change which adds functionality)
• [x] Breaking change (fix or feature that would cause existing functionality to not work as expected)

Checklist:

• [x] I have performed a self-review of my own code
• [x] I have added tests that prove my fix is effective or that my feature works

[AnnaDodson]

Production builds now zip all Lambda functions rather than just a single one.

@meridiani - we discussed this on HVT, does this work with the deployment pipeline you wanted designing?

Is this how MOTH is deploying? We're currently building one lambda per zip file too.

[JoshuaLicense]

@AnnaDodson MOTH doesn't have a pipeline at the moment. For context, the draft PRs are the ones that are still in progress until they are tested on infrastructure.

I agree with the one zip per Lambda though - so this bit likely change to 3 zips.