[tools] Add push_release script to drake

[svenevs]

Relates: #17736.

• This is the current version (ready for focal + jammy) on s3.
• Only change: user must manually set gpg_key variable for now, comments added to explain.

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This change is 

[BetsyMcPhail]

tools/release_engineering/dev/push_release line 126 at r1 (raw file):

Previously, svenevs (Stephen McDowell) wrote…

FYI new file location, for review it would be worth double checking against the scripts/push_release.

I moved this to AWS/secrets/push_release