Feature Request: Allow Ignoring Specific Lines or Blocks in Formatting

[leinardi]

Description

It would be helpful if rain fmt supported a way to ignore specific lines or blocks in a CloudFormation template. This is useful when formatting needs to be skipped for certain parts of the file due to external constraints (e.g., manually controlled formatting).

Proposed Solutions

Many linters support this through inline comments. For example:

• Ignoring a single line:

  Resources:
    MyBucket:
      Type: AWS::S3::Bucket  # rain disable-line

• Ignoring a block:

  # rain disable
  Resources:
    MyBucket:
      Type: AWS::S3::Bucket
      Properties:
        BucketName: MyCustomBucket
  # rain enable

• Ignoring an entire file:

  # rain disable-file

This behavior is similar to tools like yamllint, which use structured comments to temporarily disable specific checks.

Benefit

• Enables finer control over formatting.
• Helps preserve intentional formatting decisions.
• Avoids the need for workarounds like separating specific parts into external files.