Add subtle table cell borders

[RandomFractals]

see #57

Alternatively, default to table display without cell borders display for cleaner data view and let users change it via data.table.cell.border = true or similar setting.

Ideally, we would add data.table settings change handler in extension.ts and create config.ts similar to how we did it in snippets viewer for us to load this and table height setting described in #55

see: https://github.com/RandomFractals/vscode-snippets-viewer/blob/main/src/config.ts

[usernamehw]

createRendererMessaging requires proposed api enabled. It will be Stable after 1.59.

To send a message, edit package.json:

"activationEvents": [
  "onRenderer:vscode-data-table"
],
"contributes": {
    "notebookRenderer": [
      {
        "id": "vscode-data-table",
        // ...
        "requiresMessaging": "optional",// <==
      }
    ]
}

In extension.ts

const rendererMessaging = notebooks.createRendererMessaging('vscode-data-table');
rendererMessaging.onDidReceiveMessage(handleMessage);
function handleMessage(msg: any) {

}

In renderer/index.ts

context.postMessage?.('msg');

[RandomFractals]

let's wait till vscode v1.59 is released to implement these changes.

I'll update vscode dev dependencies and notebook api libs in #63 for now, if that helps.

[RandomFractals]

@usernamehw I am closing this since built-in vscode table styles also use alternating row bg colors and no borders either. I think doing both is too much cognitively, and not worth the extra effort for the current data table display.