FIX: Stringer in RawCheckpoint and correct checkpointing module ModuleName

[vitsalis]

This PR fixes build errors introduced by #5 and #8

More specifically, initially there was this error related to the RawCheckpoint message.

>>> ignite chain serve --reset-once --verbose
cannot build app:

    [stack_trace]
# github.com/babylonchain/babylon/x/checkpointing/types
../../x/checkpointing/types/checkpoint.pb.go:85:51: cannot use m (variable of type *RawCheckpoint) as type "github.com/gogo/protobuf/proto".Message in argument to xxx_messageInfo_RawCheckpoint.Marshal:
        *RawCheckpoint does not implement "github.com/gogo/protobuf/proto".Message (missing String method)
../../x/checkpointing/types/checkpoint.pb.go:96:38: cannot use m (variable of type *RawCheckpoint) as type "github.com/gogo/protobuf/proto".Message in argument to xxx_messageInfo_RawCheckpoint.Merge:
        *RawCheckpoint does not implement "github.com/gogo/protobuf/proto".Message (missing String method)
../../x/checkpointing/types/checkpoint.pb.go:102:47: cannot use m (variable of type *RawCheckpoint) as type "github.com/gogo/protobuf/proto".Message in argument to xxx_messageInfo_RawCheckpoint.DiscardUnknown:
        *RawCheckpoint does not implement "github.com/gogo/protobuf/proto".Message (missing String method)
../../x/checkpointing/types/checkpoint.pb.go:219:21: cannot use (*RawCheckpoint)(nil) (value of type *RawCheckpoint) as type "github.com/gogo/protobuf/proto".Message in argument to proto.RegisterType:
        *RawCheckpoint does not implement "github.com/gogo/protobuf/proto".Message (missing String method)
: exit status 2

This seems to be introduced by the RawCheckpoint message not having a stringer method due to a config.

Afterwards, the build was failing due to the following error:

>>> ignite chain serve --reset-once --verbose
panic: route expressions can only contain alphanumeric characters

[stack_trace]

This was due to the ModuleName attribute containing a ..

[KonradStaniec]

This is probably good time to have task to introduce CI which will at least have building step :)
Few remarks:

1. Ine general I would check if code builds by running make build as this is something we will use
2. Even on this branch when I run make build I got error x/epoching/types/query.pb.gw.go:144:31: undefined: metadata

[vitsalis]

Yep, agreed.

The error happens because make proto-gen needs to run first. Seems that ignite is generating different proto files than what make proto-gen does. Committed an update to fix that as well.