feat(batch): ensure user-facing context is always present for external system errors

[kwannoel]

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What's changed and what's your intention?

Closes #18860

This PR adds a new macro def_anyhow_variant. The semantics of it is to construct a newtype error (same as def_anyhow_newtype), and also implement the From trait for each variant of the newtype to the parent error, which the newtype is a variant of.

Using this, we create the BatchExternalSystemError, and also allow types which are variants of it to be cast into BatchError, which ExternalSystemError is a variant of.

Checklist

• I have written necessary rustdoc comments
• I have added necessary unit tests and integration tests
• I have added test labels as necessary. See details.
• I have added fuzzing tests or opened an issue to track them. (Optional, recommended for new SQL features Sqlsmith: Sql feature generation #7934).
• My PR contains breaking changes. (If it deprecates some features, please create a tracking issue to remove them in the future).
• All checks passed in ./risedev check (or alias, ./risedev c)
• My PR changes performance-critical code. (Please run macro/micro-benchmarks and show the results.)

• My PR contains critical fixes that are necessary to be merged into the latest release. (Please check out the details)

Documentation

• My PR needs documentation updates. (Please use the Release note section below to summarize the impact on users)

Release note

If this PR includes changes that directly affect users or other significant modifications relevant to the community, kindly draft a release note to provide a concise summary of these changes. Please prioritize highlighting the impact these changes will have on users.

[kwannoel]

Macro expansion

#[derive(::thiserror::Error, ::std::fmt::Debug)]
#[error(transparent)]
pub struct BatchExternalSystemError
(#[from]
 #[backtrace]   ::anyhow::Error);
impl BatchExternalSystemError
{
    ///   Unwrap the newtype to get the inner  [` anyhow::Error `] . 
    pub fn into_inner(self) -> ::anyhow::Error {
        self.0
    }

    ///   Get the type name of the inner error. 
    pub fn variant_name(&self) -> &'static str {
        if self.0.downcast_ref::<tokio_postgres::Error>().is_some() {
            return "tokio_postgres::Error";
        }
        if self.0.downcast_ref::<iceberg::Error>().is_some() {
            return "iceberg::Error";
        }
        if self.0.downcast_ref::<ParquetError>().is_some() {
            return "ParquetError";
        }
        return "connector_error";
    }
}
impl From<tokio_postgres::Error> for BatchExternalSystemError
{
    fn from(error: tokio_postgres::Error) -> Self {
        Self(::anyhow::Error::new(error).context("Postgres error"))
    }
}
impl From<iceberg::Error> for BatchExternalSystemError
{
    fn from(error: iceberg::Error) -> Self {
        Self(::anyhow::Error::new(error).context("Iceberg error"))
    }
}
impl From<ParquetError> for BatchExternalSystemError
{
    fn from(error: ParquetError) -> Self {
        Self(::anyhow::Error::new(error).context("Parquet error"
        ))
    }
}
impl From<tokio_postgres::Error> for BatchError {
    fn from(error: tokio_postgres::Error) -> Self {
        BatchError::ExternalSystemError(BatchExternalSystemError::from(error))
    }
}
impl From<iceberg::Error> for BatchError {
    fn from(error: iceberg::Error) -> Self {
        BatchError::ExternalSystemError(BatchExternalSystemError::from(error))
    }
}
impl From<ParquetError> for BatchError {
    fn from(error: ParquetError) -> Self {
        BatchError::ExternalSystemError(BatchExternalSystemError::from(error))
    }
}

[BugenZhao]

LGTM