research: refactor adapter/wallet `initialize()`

[mrnerdhair]

• Makes initialize() on adapters private and removes unnecessary dummy implementations
• Makes initialize() on wallets always return a boolean
• On adapters with do have initialize(), it consistently turns a single device into a wallet. pairDevice() now picks the default device and delegates to wallet creation to initialize().

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[mrnerdhair]

for reference, I've checked axiom and platform-shared and neither use the return value of initialize() at all (beyond awaiting it).

[mrnerdhair]

I've reopened this as a draft; will be doing some refactoring to work towards making this non-breaking. My goal is to get to an Adapter<WalletType extends HDWallet> type in core to replace e.g. https://github.com/shapeshift/web/blob/60ffe3ffaa2e2198c72ad475dabbdcaa88d65819/src/context/WalletProvider/WalletProvider.tsx#L20-L23

[0xean]

closing as stale draft PR