CBG-3913 replace parseStreamWithXattr with sg-bucket function

[torcolvin]

Depends on https://github.com/couchbase/sg-bucket/pull/122 and https://github.com/couchbase/sg-bucket/pull/123

• Consolidate tests into a table driven test, these tests exist in sg-bucket too with just DecodeValueWithXattrs.
• Replace errors with sgbucket errors and use errors.Is

Pre-review checklist

• [x] Removed debug logging (fmt.Print, log.Print, ...)
• [x] Logging sensitive data? Make sure it's tagged (e.g. base.UD(docID), base.MD(dbName))
• [x] Updated relevant information in the API specifications (such as endpoint descriptions, schemas, ...) in docs/api

Dependencies (if applicable)

• [x] Link upstream PRs
• [ ] Update Go module dependencies when merged

Integration Tests

• [x] GSI=true,xattrs=true https://jenkins.sgwdev.com/job/SyncGateway-Integration/2406/

[torcolvin]

I was thinking about changing sgbucket.DecodeValueWithXattrs to return map[string][]byte for xattr values so the caller doesn't have to loop over them again.