fix: use Edge Bundler to merge edge function declarations (#5551)

* fix: use Edge Bundler to merge edge function declarations

* chore: update @netlify/edge-bundler

* chore: update @netlify/edge-bundler

* fix: pass `functionConfig` to `generateManifest`

* feat: send `functionConfig` property to `generateManifest`

* chore: update edge-bundler to 8.12.1

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Co-authored-by: Daniel Tschinder <231804+danez@users.noreply.github.com>

Author: eduardoboucas