Can't build browser wallet wCCD example on Windows

[Radiokot]

Bug Description I'm trying to follow the build instruction in order to run the wCCD example, but the yarn build command fails.

Steps to Reproduce

• Clone the https://github.com/Concordium/concordium-browser-wallet repository
• Run yarn in the root directory, wait for all the dependencies to be installed
• Go to the examples/wCCD directory
• Run yarn, wait for all the dependencies to be installed
• Run yarn build

Expected Result The app is built successfully and can be launched by yarn start

Actual Result The build fails with the following error:

✘ [ERROR] Could not resolve "@concordium/browser-wallet-api-helpers"

    ../../node_modules/@concordium/wallet-connectors/dist/BrowserWallet.js:13:45:
      13 │ ..._wallet_api_helpers_1 = require("@concordium/browser-wallet-api-helpers");
         ╵                                    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

  You can mark the path "@concordium/browser-wallet-api-helpers" as external to exclude
  it from the bundle, which will remove this error. You can also surround this "require"
  call with a try/catch block to handle this failure at run-time instead of bundle-time.

The build output contains the incomplete index.html file, which does nothing when started with yarn start

Versions

• Software Version: a834753
• OS: Windows 10
• Browser: MS Edge
• Mobile device, if applicable: No

[Radiokot]

It turned out that in order to build the example, you have to first run yarn build in the packages/browser-wallet-api-helpers directory. Consider adding this step to the wCCD build guide.

[dg-concordium]

@shjortConcordium Readme in the BW also needs to be updated.