feat: add solana support to metamask

[arlert-armin]

Summary

This PR adds Solana support to the MetaMask Provider by implementing the Wallet Standard. The core challenge was a mismatch between the method signatures and behavior of our previous default injected provider instance and the new Wallet Standard-based instance.

To unblock this high-priority integration, the initial implementation includes:

1. A custom SolanaSigner class, as the signer methods (e.g., signMessage, signTransaction) on the Wallet Standard instance are different from those on our legacy injected provider.
2. A temporary set of custom actions to handle Solana-specific operations through the new Wallet Standard interface.

This is a stopgap solution. The long-term plan is to deprecate this custom code once Wallet Standard support is fully integrated and standardized into the core, at which point we will use the core actions instead.

Fixes # (issue)

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Please describe the tests that you ran to verify your changes. Provide instructions so we can reproduce. Please also list any relevant details for your test configuration

• Test A
• Test B

Checklist:

• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have added tests that prove my fix is effective or that my feature works
• Implemented a user interface (UI) change, referencing our Figma design to ensure pixel-perfect precision.

[RyukTheCoder]

Tnx for your contribution, just added some comments.

[RyukTheCoder]

LGTM