use `ParsedLogPath`s for files in `LogSegment`

[zachschuermann]

What changes are proposed in this pull request?

Use ParsedLogPath<FileMeta>s instead of raw FileMetas for commit_files and checkpoint_files fields in LogSegment.

Instead of

struct LogSegment {
    commit_files: Vec<FileMeta>,
    checkpoint_files: Vec<FileMeta>,
    // ...
}

we now have

struct LogSegment {
    commit_files: Vec<ParsedLogPath<FileMeta>>,
    checkpoint_files: Vec<ParsedLogPath<FileMeta>>,
    // ...
}

How was this change tested?

exisitng

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 78.95%. Comparing base (785b9dd) to head (daf7fce). Report is 1 commits behind head on main.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #472 +/- ## ======================================= Coverage 78.95% 78.95% ======================================= Files 56 56 Lines 12214 12216 +2 Branches 12214 12216 +2 ======================================= + Hits 9643 9645 +2 Misses 2052 2052 Partials 519 519 ```

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