Introduce justfile over Makefile

[ross-spencer]

Install with:

cargo install just

Basic outline:

# Get help
help:
  just -l

# Recipe `do` help text
do:
  @echo "do"

# Do not...
do-not: do
  @echo "or do not"

# Try this...
try: 
  @echo "there is no try"

[ross-spencer]

Note, pre-commit checks are missing from the Makefile:

# Run all pre-commit checks
all-checks:     
	pre-commit run --all-files

# Run pre-commit spelling check
spell:          
	pre-commit run codespell --all-files

# Run pre-commit makdown-lint
markdown:       
	pre-commit run markdownlint --all-files