[Bug Fix]: Updating webview CSP + webpack sourcemapping overrides

[mliao95]

This PR updates the content-src CSP to allow URLs with data: prefixes. It also updates webpack sourcemapping to account for webpack:// resource prefixes.

These changes should help improve compatibility of the extension with projects using webpack.

[bgoddar]

Looks like there are also places in sourcemaps.md and utils.ts that need updating:

export const SETTINGS_DEFAULT_PATH_OVERRIDES: IStringDictionary<string> = {
    'meteor://💻app/*': '${webRoot}/*',
    'webpack:///*': '*',
    'webpack:///./*': '${webRoot}/*',
    'webpack:///./~/*': '${webRoot}/node_modules/*',
    'webpack:///src/*': '${webRoot}/*',
};

and sourcempas.md

"sourceMapPathOverrides": {
    "webpack:///./~/*": "${webRoot}/node_modules/*",
    "webpack:///./*": "${webRoot}/*",
    "webpack:///*": "*",
    "webpack:///src/*": "${webRoot}/*",
    "meteor://💻app/*": "${webRoot}/*"
}

[bgoddar]

LGTM!