chore: log a warning when DataStore is ignoring an attempted PK update

[svidgen]

Description of changes

DataStore does not update PK values on existing records. This behavior is by design, but has proven to be confusing when customers are not aware of it. This PR attempts to inform customers by logging a warning when a copyOf invocation attempts to update a PK field.

Warnings will look similar to this:

[WARN] 32:03.272 DataStore - copyOf() does not update PK fields. The 'id' update is being ignored. {
  source: Model {
    field1: 'something',
    dateCreated: '2022-12-09T16:32:03.272Z',
    id: 'b47c45a9-7ac4-405b-a07f-152fda83813c',
    _version: undefined,
    _lastChangedAt: undefined,
    _deleted: undefined
  }
}

We considered changes to this save() behavior to update the item, create a new item, or throw an error. But, these have been deemed breaking changes. This change will provide some guidance without breaking changes.

Issue #, if available

Description of how you validated changes

Added tests to spy on console warn calls.

Checklist

• PR description included
• yarn test passes
• Tests are changed or added
• Relevant documentation is changed or added (and PR referenced)

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[codecov-commenter]

Codecov Report

Merging #10756 (8eff711) into main (4725b5f) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##             main   #10756   +/-   ##
=======================================
  Coverage   86.16%   86.16%           
=======================================
  Files         196      196           
  Lines       18351    18354    +3     
  Branches     3905     3906    +1     
=======================================
+ Hits        15812    15815    +3     
  Misses       2464     2464           
  Partials       75       75           

Impacted Files	Coverage Δ
packages/datastore/src/datastore/datastore.ts	88.36% <100.00%> (+0.03%)	⬆️

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[iartemiev]

LGTM 👍🏻