fix(docker): multi-architecture image build

[EugeneTorap]

SUMMARY

We have a problem with multi-architecture image building:

docker buildx build --no-cache --platform=linux/amd64,linux/arm64 --rm -t superset --push .

Because we build first stage twice on amd64 and arm64 arch
This PR provides --platform=$BUILDPLATFORM flag in UI layer that ensures that this stage is build once and reuse at the second layer even if we do a multi-arch build. It's Cross-Compilation image building

Useful Article - https://www.docker.com/blog/faster-multi-platform-builds-dockerfile-cross-compilation-guide/

BEFORE/AFTER SCREENSHOTS OR ANIMATED GIF

Blue contains x86 binaries, yellow ARM binaries.

TESTING INSTRUCTIONS

ADDITIONAL INFORMATION

• Has associated issue:
• Required feature flags:
• Changes UI
• Includes DB Migration (follow approval process in SIP-59)
  • Migration is atomic, supports rollback & is backwards-compatible
  • Confirm DB migration upgrade and downgrade tested
  • Runtime estimates and downtime expectations provided
• Introduces new feature or API
• Removes existing feature or API