Include FCL-WC by default

[jribbink]

Feature

We should include FCL-WC in the @onflow/fcl library by default. Developers should configure their client ID within the FCL configuration, as a prerequisite for the plugin to be activated. If they do not configure, we should prompt them to do so using warning messages.

Context

Flow Wallet is the flagship wallet of Flow. Its mobile offering is not currently supported by FCL by default, as it relies on WalletConnect. This creates an issue, as many dApps on Flow do not use the WalletConnect plugin, thus do not support Flow Wallet. We need to resolve this issues so that users can use the wallet of their choosing on any dApp, and not just those which support FCL-WC.