Pass additional information for logger when formatting snippets

[mgroth0]

Description

I generate multiple kotlin files in a large gradle build with custom gradle tasks. The final step of the kotlin code generation uses ktlint to format the code before it is written to a file. As such, the code is passed to ktlint using Code.fromSnippet. This normally works, but occasionally I get log warning messages such as:

Format was not able to resolve all violations which (theoretically) can be autocorrected in file <stdin>

The issue is that I cannot determine which one of the generated files is causing this issue. This PR adds an optional parameter to allow passing more information to this log message.

Checklist

Before submitting the PR, please check following (checks which are not relevant may be ignored):

• Commit message are well written. In addition to a short title, the commit message also explain why a change is made.
• At least one commit message contains a reference Closes #<xxx> or Fixes #<xxx> (replace<xxx> with issue number)
• Tests are added
• KtLint format has been applied on source code itself and violations are fixed
• PR title is short and clear (it is used as description in the release changelog)
• PR description added (background information)

Documentation is updated. See difference between snapshot and release documentation

• Snapshot documentation in case documentation is to be released together with a code change
• Release documentation in case documentation is related to a released version of ktlint and has to be published as soon as the change is merged to master

[mgroth0]

This might be the wrong solution. Its possible there could be multiple generated files with the same name and that the issue of not being able to identify which file has the issue would persist.

Another idea I had originally was to allow passing an optional handler so that the behavior for Format was not able to resolve all violations can be customized. The default would still be to log it at the warning level as it does now, but the api consumer could optionally handle it a different way, even throwing an exception if it choses, by passing a lambda. I decided to try the current solution instead because it seemed like an easier change, but I'm unsure that its sufficient.