fix: reduced unnecessary GET /sketches request

[kittaakos]

Motivation

This PR slightly modifies the implementation of arduino/arduino-ide#875 to reduce the unnecessary GET /sketches. The endpoint claims to support pagination, but it does not. So if the number of sketches can be divided by the limit without a remainder, another fetch is required.

This PR does not change the limit but leaves it at 50. This PR adds tests to verify the new behavior. Note that those tests do not run on the CI, only locally when secrets are set in the environment.

To verify:

• you have more than 50 sketches on https://create.arduino.cc/editor,
• open IDE2 and log in to the cloud, and
• verify that you see all you sketches in the cloud sketchbook tree.

Change description

Other information

Reviewer checklist

• PR addresses a single concern.
• The PR has no duplicates (please search among the Pull Requests before creating one)
• PR title and description are properly filled.
• Docs have been added / updated (for bug fixes / features)

[per1234]

Nice refactoring Akos!