feat: Cleaner gasless implementation

[GabrielePicco]

Greptile Summary

Implemented a gasless transaction handling mechanism in the magicblock-validator, focusing on fee payer account management and transaction processing.

• Modified bank.rs to add unsafe_create_account_overrides function and inject temporary fee payer accounts with 100 lamports
• Reduced initial payer SOL allocation from 1,000 to 1 in ephem-localnet.toml for testing gasless scenarios
• Added test case in transaction_execute.rs to verify transactions with non-existent fee payers and zero fees
• Changed solana-svm dependency to use custom Git repository for modified VM handling
• Made create_noop_instruction public in transactions.rs for broader testing access

Note: The implementation uses unsafe code to modify private fields which should be reviewed carefully for memory safety.

[greptile-apps]

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[greptile-apps]

logic: Missing commit hash/revision for Git dependency. Add a rev = "..." field to ensure dependency stability.

Suggested change

	solana-svm = { git = "https://github.com/magicblock-labs/magicblock-svm.git", features = [ "dev-context-only-utils" ] }
	solana-svm = { git = "https://github.com/magicblock-labs/magicblock-svm.git", rev = "HEAD", features = [ "dev-context-only-utils" ] }