Disable memoization for specific requests

[rerinho]

Hello!

Changes:

1. Added memoize option in the Request type (its true by default for GET requests)
2. Added request memoizable validation before the response is set in memoisedResults.
3. Added 3 tests
   a. When no memoize option is informed (only for non-GET requests)
   b. When memoize option is false (should not add the response in the memoizedResults)
   c. When memoize option is true (current version default approach)

Motivation:

This change was necessary for a specific use case presented bellow:

1. Request a resource from another API.
2. Update some property of this resource.
3. Request the same resource again.

In this case, the resource received in the step 3 will be the same as in step 1, as the memoized is returned.

The memoize option allows to disabling storage in memoizedResults for specific requests.

[contesini]

LGTM

[joaoantoniosouza]

LGTM

[JustinTRoss]

Good work! 💪 This feature is dearly needed.

[JustinTRoss]

Is there anywhere we can find a list of maintainers who can approve the running of workflows? @StarpTech

[StarpTech]

Hi @JustinTRoss, I'll try to review it next week. Thanks for the work.

[JustinTRoss]

Thanks @StarpTech 🙏 . @rerinho is the hard-worker 🔨 . Just looking for the lever to advance this to the next step 🙃 .

[StarpTech]

LGTM except for a small thing. Great PR.

[StarpTech]

LGTM

[StarpTech]

https://github.com/StarpTech/apollo-datasource-http/releases/tag/0.19.0