Add a compatibility package to allow registering legacy wallet adapters as standard wallets

[wjthieme]

This is an example implementation of an Adapter wrapper that conforms to Wallet. This allows registering any Adapter from @solana/wallet-adapter-wallets in a @wallet-standard/base Wallet.

This is potentially useful in the following scenarios:

• Some 'wallets' cannot register as standard wallet as they are not installed as browser extensions (WalletConnect, Moongate, etc.). This allows those adapters to be used without requiring an updated from the creators of those wallet adapters (which might take a while).
• This allows for a more simple upgrade path from @solana/wallet-adapter-react to @wallet-standard/<> packages since there is no dependency on adapters to upgrade their code.
• This would allow lazily registering any wallet adapter into @wallet-standard by just registering the adapter wrapper on demand (for example right before the user wants to connect). The implementation for this would need to provide name + icon since they are then no longer available from the wrapper (since it is not loaded yet).

This PR merely serves as an example. There at least a few kinks that need to be worked out as well as some testing before there can be any talk about proceeding with this.

cc @jordaaash @steveluscher

[wjthieme]

@steveluscher thanks for the feedback!

The only other meta piece of feedback I have to offer (without actually having inspected the situation too closely) is that there's a lot of ! assertions everywhere. The target number of ! assertions, on the internet, should be zero. I have to believe that there's either something we can do to eliminate those, or worse that the presence of those is burying a bug.

Not really sure why I added all the ! assertions since they're not even doing anything (type-wise) seeing that Array[number] doesn't return x | undefined but just x. Anyway with interleaving they can be removed either way