Fix #7049: P5.Graphics.remove() doesn't release all related resources

[iambiancafonseca]

Resolves #7049

Changes:

• Modified the remove() method in src/core/p5.Graphics.js to set this._renderer, this.canvas, and this.elt to undefined.
• Updated documentation in src/core/p5.Graphics.js accordingly.
• Added a boolean variable doubleClickedBool to track whether the graphics object has been removed due to a double-click event.
• Added unit test in test/unit/core/p5.Graphics.js to cover scenario described in the issue.

Now when we call remove() all associated resources should be released.

Screenshots of the change: (no screenshots)

PR Checklist

• [x] npm run lint passes
• [x] [Inline documentation] is included / updated
• [x] [Unit tests] are included / updated

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[davepagurek]

Thanks for making this change and adding tests! Just one minor note about the example.

[davepagurek]

@all-contributors please add @iambiancafonseca for docs

[allcontributors[bot]]

@davepagurek

I've put up a pull request to add @iambiancafonseca! :tada: