Support publishing sourcemaps

[hajekj]

We want to be able to effectively debug PCFs in production without including in-line sourcemap. So the sourcemap should be included with the solution even in production build (it doesn't get loaded in the browser unless F12 Developer Tools are open).

• Provide custom webpack.config.base.js (sort of a template file) which can be referenced in control's own (based on this for example)
• Ensure that the the sourcemap is generated for production builds
• Development builds should use inline sourcemap (so it's easier to load with Fiddler)
• Ensure the sourcemap is included in the solution
  • It doesn't get included in the solution unless specified in ControlManifest.xml (it's ignored). The only viable way is to specify it as html which is not supported in canvas
  • This has to however be done post pcf-scripts build/rebuild because build outputs are copied to out/ based on manifest, and bundle.js.map gets outputted there directly from webpack
• Ensure the sourcemap is used when loaded in Power Apps in the browser
• Document this process into README
• Ensure our metadata service (INT0014) can provide the sourcemaps via /webresource/* endpoint

The created webpack.config.base.js should look like this. getBuildMode should be also exported.

export const getBuildMode = () => {
    const cliArgs = process.argv;
    const indexOfMode = cliArgs.findIndex(x => x.includes("--buildMode"));
    return cliArgs[indexOfMode + 1].replaceAll("\"", "");
};

export const extendWebpackConfig = (customConfig) => {
    customConfig.devtool = getBuildMode() === "production" ? "source-map" : "inline-source-map";
};

The consumer should be able to use it in their webpack.config.js following way:

import { extendWebpackConfig } from "@talxis/pcf-preset-base/webpack.config.base.js`;

const customConfig = {};
extendWebpackConfig(customConfig);
module.exports = customConfig;

There is an issue with shipping sourcemaps, since all the PCF use the same namespace pcf_tools_652ac3f36e1e4bca82eb3c1dc44e6fad which can result in conflicting dependency names.