[wallet-adapter] merge wallet adapter (MystenLabs#3361)

* [wallet-adapter] initial merge

wallet-adapter/.gitignore

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+# See https://help.github.com/articles/ignoring-files/ for more about ignoring files.
+
+# dependencies
+/node_modules
+/.pnp
+.pnp.js
+
+# testing
+/coverage
+
+# production
+/build
+
+# misc
+.DS_Store
+.env.local
+.env.development.local
+.env.test.local
+.env.production.local
+
+npm-debug.log*
+yarn-debug.log*
+yarn-error.log*

wallet-adapter/README.md

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+# Sui Wallet Adapter
+
+This project is an adapter for wallets on the Sui blockchain.
+
+### Modules
+
+#### packages/adapters/base-adapter
+Defines the base interface in which the wallet adapters will implement.
+
+#### packages/adapters/integrations
+Contains the integrations for each wallet. If you are importing multiple wallets, it may be beneficial to instead import the `all-wallets` module, which exports all integrated wallet adapter interfaces.
+
+#### packages/ui
+Contains basic UI elements such as the Connect/Manage Wallet and corresponding modals for each wallet. Check out ./src for an example of how to integrate this to your project.
+
+#### packages/react-providers
+Contains the react providers that inject the endpoint defined in `packages/adapters/base-adapter` into your project. Check out ./src for an example of how to integrate this to your project.