mark_as_read api inconsistent with file api

[odgrim]

Describe the enhancement

Right now mark_as_read requires an absolute path to function correctly but file can use a relpath. The docs (until very recently) explain the desired usage pattern is something like file(mark_as_read('myfile.txt')). If we use a relpath for this then this has the opportunity to break!

The inconsistency of api for both mark_as_read vs file is a UX issue.

Example breaking code (ignore the lack of fileset here- I didn't write it!)

locals {
  _all_files        = split("\n", run_cmd("--terragrunt-quiet", "ls", "-p", "src"))
  _all_files_marked = [for f in local._all_files : mark_as_read("src/${f}")]
}

Example that correctly marks as read:

locals {
  _all_files        = split("\n", run_cmd("--terragrunt-quiet", "ls", "-p", "src"))
  _all_files_marked = [for f in local._all_files : mark_as_read(abspath("${get_terragrunt_dir()}/src/${f}"))]
}

Additional context

Flagged by a customer relying on tf files in their infrastructure live repo.

Link to a Proof of Concept if you have one:

• PoC

Including a PoC can help others understand the feature better and implement it faster.

RFC Not Needed

• I have evaluated the complexity of this enhancement, and I believe it does not require an RFC.