Include tools to create mizuRoute input files as part of the mizuRoute checkout

This will be needed for CESM4 in order for mizuRoute to be the CESM river component for CESM4. We will need to have tools available for making mizuRoute input files: network files, mesh files, and mapping files for custom grids for mizuRoute. The tools could be in their own repository and checked out in an externals config file, or just included directly in mizuRoute (for example under a "tools" subdirectory as we do in CTSM).

There are currently python scripts to do the following things, we just need them added to the checkout. We can check in the initial versions as they are, and then in time clean them up, add testing, and usability changes to them.

Definition of Done:
- [ ] Have tools to create network files in the checkout
- [ ] Have tools to create mesh files in the checkout
- [ ] Have tools to create mapping files in the checkout
- [ ] Add testing for the tools
- [ ] Possibly create a structure similar to the "python" directory for CTSM where python scripts can have testing and black and pylint checking done on them (This and the last possibly should be their own issue if this is decided to be done)...