Add full support for Serverless Framework v4 (and native build.esbuild)

[BuhayovA]

When using serverless-offline-sns with the current Serverless Framework v4 (≥ 4.0.0), the plugin crashes during startup

Plugin is not aware of the framework’s native esbuild lifecycle.
If we dont apply a manual “esbuild workaround”, Lambda code isn’t bundled at all, so the service boots with empty handler files and fails immediately.

Error: Cannot find module 'src/handler.js'      # Lambda file never built

Current “must-have” hack

// serverless.ts
build: { esbuild: false }          # ⬅ disable v4 native builder
plugins: ["serverless-esbuild"]            # ⬅ old plugin as a replacement

Could you please add v4-compatible build handling (or at least document the requirement)?
Right now without the hack Lambda files never compile, leading to a fatal “handler not found” error during sls offline startup.