feat: smart sessions abstractions 1

[vr16x]

PR-Codex overview

This PR focuses on enhancing the functionality of multichain account actions and policies in the SDK. It includes improvements to error messages, introduces new action policies, and adds tests for various scenarios involving multichain actions.

Detailed summary

• Updated error messages for nonce validation in getQuote.ts.
• Enhanced buildActionPolicy and buildAction functions in toMultiChainNexusAccount.ts.
• Added tests for new action policies in buildActionPolicy.test.ts.
• Introduced erc20SpendingLimit action type with specific constraints.
• Refactored prepareForTestnetSmartSessions to support custom actions.
• Added comprehensive tests for action building in buildAction.test.ts.

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[github-actions]

size-limit report 📦

Path	Size
core (esm)	66.59 KB (+1.09% 🔺)
core (cjs)	80.96 KB (+0.85% 🔺)
bundler (tree-shaking)	6.65 KB (0%)
paymaster (tree-shaking)	543 B (0%)