global-endpoint: Refactor to auto-allocate badges

As the global-endpoint is a notification object shared across multiple
camkes connections, we force each connection end to have a distinct
badge value and don't allow the camkes assembly to specify badge values
or notification object names.

templates: Standardize use of assigning badges

Don't require ${interface_name}_attributes to be set in every case. The
'from' ends don't typically need to control what badge they appear under
in the 'to' end and it is easier to allow the connector to allocate
badges itself. Note: it may still be required to force badge assignment
in order to link separate interfaces together and so this mechanism is
still supported.

components: Changes related to MAC address config

1. Remove the need for users to provide MAC address for ethdriver
initialization
2. Providing MAC address is now optional for clients of ethdriver,
if a client does not provide a MAC address, it is configured to
use the device MAC address

templates: Sort badges as integer types

Without storing badges as ints, they get sorted lexicographically
instead of numerical.

templates: Add Ethdriver related connectors

This commit moves the Ethdriver related connectors from the camkes-vm
repository over to this repository. Additionally, the "seL4Ethdriver-to"
is refactored to remove duplicate code.