Major project upgrade

[WillPoulson]

Includes the following:

• Upgrades the project to Angular 11.
• Updates to use @ionic/storage-angular as recommended by ionic.
• Updates to latest Karma and Jasmine.
• Allows the angular cli to be used with ng-packagr bundling the package.
• Rewrites lots of the test cases. (Sadly missing a few, contributions welcome as always).
• Changes the tslint rules to the recommended with a new angular project.
• Removes broken circle ci config (Was trying to use yarn which was removed awhile ago).
• Updates editorconfig to generated angular standard.
• Updates gitignore to generated angular standard.

Unfortunately lots of these changes all had to be done at the same time. It was impossible to upgrade one without the other.

I completely understand if this PR is declined due to the huge amount changes. If this is the case I'll upload my fork to npm under @WillPoulson/ionic-cache to allow others wanting to upgrade to install it.

[Nodonisko]

Wow, thanks a lot! Really nice work. I think we can merge this.