De-reference the constructor from the rendering of VariableExplorerButtonCellFormatter

[sadasant]

The VariableExplorerButtonCellFormatter is currently tying the constructor of the VariableExplorer in: https://github.com/microsoft/vscode-jupyter/blob/main/src/webviews/webview-side/interactive-common/variableExplorer.tsx#L125

We should not take the reference from the constructor, for performance reasons.
(though I haven't tested this kind of performance in a while, but seems reasonable to move this state-referencing out of the constructor)

[DonJayamanne]

To my knowledge this kind of this only impacts perf in react only when dealing with components that get rendered 100s if not 1000s of times e.g. within a cell of a grid.
The variable explorer here is a top level component, hence i don't think this will introduce any perf issues,

e reference from the constructor, for performance reasons.(though I haven't tested this kind of performance in a while,

personally i'd like to see the perf impact on this, as I don't think there is any.
Meaning users will not be impacted in any way, thus making this more of a debt than a perf or even a paper cut issue (because perf or papercut would imply its proven to be a problem, but something we can live with)

[sadasant]

@DonJayamanne You may be correct! I made this issue to keep the open question and come back to it later.

However, since our goal is to re-enable the data viewer on the web asap, this issue will be fixed soon when we remove the isWeb clause on that component. So, we can forget about this!

Thank you for taking the time to think it through though.

[DonJayamanne]

Should we then close this issue?

[sadasant]

Yup yup! Thanks!