Create reusable workflow for preview deploys

[elliotBraem]

Bigger teams like to include preview deploys in their pull requests; this typically involves the developer deploying to a dedicated account and sharing a link -- although this can be difficult when working on multiple stories at one time (either needs a dedicated account per story, or need to rotate through the deploys depending on the order they are reviewed).

A possible solution (only in testnet) is to create github workflow that generates an implicit account via near-cli-rs, then deploys to this account and shares the preview link automatically.

[elliotBraem]

...several months later

We can use this with the new deploy command:

bw deploy --deploy-account-id <deployAccountId> --signer-account-id <signerAccountId> --signer-public-key <signerPublicKey>" --<signerPrivateKey>

Or if we can run the dev server in a container, that would work too