feat: allow empty lines in snapshot

[George-Ogden]

Description

This PR allows empty lines in the snapshot file to be treated that way, without affecting other snapshot semantics.

Example

Say I have a test output that looks like this:

# Outputs README-like text Including empty newlines above and below <footer>Followed by a footer</footer>

This is saved in a snapshot as:

 """  # Outputs README-like text    Including empty newlines above and below    <footer>Followed by a footer</footer>  """

Therefore, there are two lines in this snapshot that include just spaces: " ".
This PR does not affect how the snapshots are saved, but if you trim the empty spaces on the blank lines, such as with a linting tool, the snapshot will load them as empty lines (currently, they are skipped).

Related Issues

• closes .ambr snapshot files have meaningful trailing whitespace #619, which asks for this feature

Checklist

• This PR has sufficient documentation.
• This PR has sufficient test coverage.
• This PR title satisfies semantic convention.

Additional Comments

No additional comments.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

@@ Coverage Diff @@ ## main #1042 +/- ## ======================================= Coverage 97.29% 97.30% ======================================= Files 21 21 Lines 1666 1669 +3 ======================================= + Hits 1621 1624 +3  Misses 45 45 

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