Add require_and_update_submodule to ensure submodules exist

This adds a new method `require_and_update_submodule` to replace
`update_submodule`. This new method will generate an error if the
submodule doesn't actually exist. This replaces some ad-hoc checks that
were performing this function. This helps ensure that a good error
message is always displayed.

This also adds require_and_update_all_submodules which does this for
all submodules.

Ideally this should not have any change other than better error messages
when submodules are missing.

0 files changed, 0 insertions, 0 deletions