Add cache to package hover details

[erropix]

Whenever I hover over a package version it starts loading the details (like the package link).

And also, when the mouse moves, the details get loaded again.

Add caching to only check for outdated packages once and display the details from the cache.

[erropix]

@mskelton any updates on this please?

[mskelton]

@erropix I don't use or maintain this extension anymore. @rentalhost has done a lot of the recent maintenance and might be able to help out.

[hpawe01]

@erropix: This has nothing to do with this extension. The package information is loaded by VSCode and this loading behavior is triggered by VSCode. Just try it out with this extension disabled. You will see, that the popup disappears for a second and appears again after VSCode loaded the package information again.

So please close this issue here and report it again in the vscode repo.