Fix CI Build By Matching Upstream

[brianmichel]

Description

This PR moves the BCNY firebase CI closer to what the upstream repo does. We move our checkout, and call into the various build scripts that the upstream repository uses in order to produce a working set of builds.

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Testing

• Take a look at test the workflow when we push a PR #8 and inspect the artifacts on the last successful fun.

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Type of Change

Place an x the applicable box:

• Bug fix. Add the issue # below if applicable.
• New feature. A non-breaking change which adds functionality.
• Other, such as a build process or documentation change.

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Notes

• Bug fixes and feature changes require an update to the Release Notes section of release_build_files/readme.md.
• Read the contribution guidelines CONTRIBUTING.md.
• Changes to the public API require an internal API review. If you'd like to help us make Firebase APIs better, please propose your change in a feature request so that we can discuss it together.

[brianmichel]

Current dependencies on/for this PR:

• compnerd/swift
  • PR Fix CI Build By Matching Upstream #6 👈
    • PR test the workflow when we push a PR #8
    • PR Test the workflow on push #7

This stack of pull requests is managed by Graphite.

[brianmichel]

Closing in favor of #12