Add dry-run flag to fmt subcommand to check for unformatted files.

[f4z3r]

1. Does this PR affect any open issues?(Y/N) and add issue references (e.g. "fix #123", "re #123".):

• N
• Y KCL fmt: add dry run option kcl#2101

2. What is the scope of this PR (e.g. component or file name):

The fmt subcommand.

3. Provide a description of the PR(e.g. more details, effects, motivations or doc link):

Adds a --dry-run flag to the fmt subcommand. If provided, the command will return a non-zero status code if unformatted files are found. Moreover, it will print the following to stderr:

X KCL file(s) require formatting

4. Are there any breaking changes?(Y/N) and describe the breaking changes(e.g. more details, motivations or doc link):

• N
• Y

5. Are there test cases for these changes?(Y/N) select and add more details, references or doc links:

• Unit test
• Integration test
• Benchmark (add benchmark stats below)
• Manual test (add detailed scripts or steps below)
• Other

[f4z3r]

Not sure the new e2e test will pass. I did not manage to get these working properly.

[f4z3r]

Not sure the new e2e test will pass. I did not manage to get these working properly.

Ok, the issue was due to a newline at the end of the input file that does not get sanitized. I am unsure if sanitation is desired, so I simply stripped it from the file.