feat: require one of check or overwrite options in format command

[Scott8440]

Requires that one of --overwrite or --check be provided and removes the default behavior of just printing the formatted files to stdout.

The --overwrite flag is now just a safety check so the caller knows that what they are doing is destructive, as writing the file is now "default" behavior, with --check being the modifier.

Test:

❯ cargo run --release format --check --overwrite ~/wdl/wdl-format/tests/format/optional_structs/
    Finished `release` profile [optimized] target(s) in 0.07s
     Running `target/release/sprocket format --check --overwrite /home/scott/wdl/wdl-format/tests/format/optional_structs/`
error: the argument '--check' cannot be used with '--overwrite'

Usage: sprocket format <--overwrite|--check> <PATH>

For more information, try '--help'.

❯ cargo run --release format ~/wdl/wdl-format/tests/format/optional_structs/ 
    Finished `release` profile [optimized] target(s) in 0.07s
     Running `target/release/sprocket format /home/scott/wdl/wdl-format/tests/format/optional_structs/`
error: the following required arguments were not provided:
  <--overwrite|--check>

Usage: sprocket format <--overwrite|--check> <PATH>

For more information, try '--help'.

[a-frantz]

Some nits over word smithing. Please commit my suggestions and then run cargo +nightly fmt after.