feat: start writing RedirectionDestination in redis cache

[dcshzj]

Problem

What problem are you trying to solve? What issue does this close?

Split from #2403

Solution

How did you solve the problem?

Features:

• Start writing RedirectDestination into the redis cache

Tests

What tests should be run to confirm functionality?

Deploy Notes

Notes regarding deployment of the contained body of work. These should note any
new dependencies, new scripts, etc.

• Must be released after feat: check for malicious link just before redirect #2403 is merged and released!

[seaerchin]

generally no issues, but can i be abit more onerous here, cos the blast radius of this chnage is huge.

would it be possible to add a test case for back-compat (so now, my values in redis are string and not json) then check that reads still work gracefully.

understand that we do a try/catch then resolve with defaults:

            resolve({
              longUrl: cacheLongUrl,
              isFile: false,
              safeBrowsingExpiry: null,
            })

but just paranoid haha

[seaerchin]

discarding my previous review, noticed existing tests use a string already