Add UriHandler to open remote tabular data sources from vscode:// Urls in a browser

[RandomFractals]

when remote data loading is implemented in #53

UriHandler docs: https://code.visualstudio.com/api/references/vscode-api#window.registerUriHandler

Sample repo: https://github.com/microsoft/vscode-extension-samples/tree/main/uri-handler-sample

[RandomFractals]

Supported Tabular Data Viewer vscode:// Url commands that can be executed directly from a browser via system-wide Urls:

• viewSettings: vscode://RandomFractalsInc.tabular-data-viewer/viewSettings
• openDataFile prompt: vscode://RandomFractalsInc.tabular-data-viewer/openDataFile
• viewTable with data file Url fragment: vscode://RandomFractalsInc.tabular-data-viewer/viewTable#https://raw.githubusercontent.com/RandomFractals/tabular-data-viewer/main/data/world-cities.csv
• viewTable with dataUrl query param: vscode://RandomFractalsInc.tabular-data-viewer/viewTable?dataUrl=https://raw.githubusercontent.com/RandomFractals/tabular-data-viewer/main/data/world-cities.csv