Add Cosmos & Solana code snippets to `Reference` section of docs

[avious00]

relevant places in docs:

• https://docs.hyperlane.xyz/docs/your-first-message
• reference section
• src/components/InteractiveExample.tsx:104: 🚧 Coming soon! 🚧
• src/components/InteractiveExample.tsx:107: 🚧 Coming soon! 🚧
• docs/reference/messaging/send.mdx:56:🚧 Coming soon! 🚧
• docs/reference/messaging/send.mdx:61:🚧 Coming soon! 🚧
• docs/reference/messaging/send.mdx:111:🚧 Coming soon! 🚧
• docs/reference/messaging/send.mdx:116:🚧 Coming soon! 🚧
• docs/reference/messaging/receive.mdx:43:🚧 Coming soon! 🚧
• docs/reference/messaging/receive.mdx:48:🚧 Coming soon! 🚧
• look for other places where Coming soon!