Improve nested error handling

[dangeross]

This PR aims to remove wrapping of error strings rendered from nested errors within the SDK. The result being only outwardly facing errors prefix their variant name to the error string

Example 1:

Generic: Failed to create invoice: Invalid amount: Receive amount must be more than 0

Invalid amount: Receive amount must be more than 0

Example 2:

Generic: Generic: status: Unknown, message: "transport error", details: [], metadata: MetadataMap { headers: {} })

Service connectivity: status: Unknown, message: "transport error", details: [], metadata: MetadataMap { headers: {} })

Inspired by #885, but may not solve the Flutter issue

[erdemyerebasmaz]

LGTM 🎉

[ok300]

Good idea! Simple and elegant solution.

Just one NIT, otherwise LGTM.

[ok300]

IMO the previous prefix was useful here, to help us pin-point this to a persister issue.

[dangeross]

So the error previously would be:
Generic: Sql: Error when accessing local DB: <rusqlite::Error>
would this be better for SQL errors?
Generic: Error when accessing local DB: <rusqlite::Error>

I would apply this to the enum so all outward facing errors get the same

pub enum PersistError {
    ...

    #[error("Error when accessing local DB: {0}")]
    Sql(String),
}

[ok300]

The top one is best:
Generic: Sql: Error when accessing local DB: <rusqlite::Error>

I was only pointing out that the Error when accessing local DB prefix seemed to be removed, as I found it nowhere else in the code.

[roeierez]

LGTM