radicle-surf: reorganise errors

The current `error::Error` type aggregated a lot of different error
scenarios that were not for the actual repo actions, instead they
would be for the domains that the repo actions would return.

This is a reorganisation of those by localising error variants in
their modules:
* namespace::Error
* commit::Error
* glob::Error
* adding `type Error` to ToCommit
* adding `type Error` to Revision

The main Error type now consists of these other Error types and lives
in the `repo` module. It is re-exported at the top-level since
RepositoryRef is the main interaction with the library.

During this refactor, some reorganisation of functions was done as
well:
* Move `get_file` from `Commit` to `RepositoryRef` as
`get_commit_file`.
* Have a blanket implementation of `ToCommit` for any `Revision`,
instead of repeating the implementations.

Signed-off-by: Fintan Halpenny <fintan.halpenny@gmail.com>
X-Clacks-Overhead: GNU Terry Pratchett

radicle-surf/src/commit.rs

@@ -27,7 +27,7 @@ use serde::{
 use crate::{
     diff,
     file_system,
-    git::{self, Glob, RepositoryRef},
+    git::{self, glob, Glob, RepositoryRef},
     person::Person,
     revision::Revision,
 };
@@ -251,7 +251,10 @@ pub enum Error {
 
     /// An error occurred during a git operation.
     #[error(transparent)]
-    Git(#[from] git::error::Error),
+    Git(#[from] git::Error),
+
+    #[error(transparent)]
+    Glob(#[from] glob::Error),
 
     /// Trying to find a file path which could not be found.
     #[error("the path '{0}' was not found")]