fix(svm): L-01 create new vault on deposit if needed

[Reinis-FRP]

OZ identified following issue:

Pull request #939 removes route-enabling functionality in the SVM Spoke, allowing depositors to provide any input token for any destination chain, not only those with the route enabled. Previously, when a route was enabled, the Associated Token Account (ATA) of the vault for user deposits would be created. The DisabledRoute error would also be generated if a user tried to deposit to a disabled route. Since, by this point, all routes would be enabled, a user may try to submit a deposit where the vault ATA has not been initialized. This will cause the deposit transaction to fail without a descriptive error message.

Thus, if the vault has not been created, the depositor would have to initialize the PDA themselves, for example, using the createVault.ts script. However, this is not a simple process for the majority of users and it may be unclear why the deposit failed. This could cause users to abandon their deposit attempt and consider alternative bridging solutions. A more straightforward solution would be to initialize the vault during deposit using the init_if_needed flag as was previously done when the admin enabled a route.

Consider adding the init_if_needed flag or clearly documenting the desired vault creation process within the docstring for the deposit function.

This PR addresses the issue by adding the init_if_needed flag to the vault account in the deposit method.

[linear]

ACX-4022 L-01 Unclear Vault Initialization Process

[md0x]

Looks great!