refactor: clean up file system entry retrieval

[jonkoops]

What kind of change does this PR introduce?

• [ ] Bug Fix
• [ ] Feature
• [x] Refactoring
• [ ] Style
• [ ] Build
• [ ] Chore
• [ ] Documentation
• [ ] CI

Did you add tests for your changes?

• [ ] Yes, my code is well tested
• [x] Not relevant

If relevant, did you update the documentation?

• [ ] Yes, I've updated the documentation
• [x] Not relevant

Summary Cleans up the code that retrieves and processes file system entries so that the flow is easier to follow. This is done by wrapping methods such as readEntries() and file() and 'promisifying' their callback style to promises, which allows them to be awaited.

Additionally, this PR re-structures the fromDirEntry() function to use the above and uses a while loop to drain the directory reader until there are no more entries to read. This simplifies the code and improves readability as it is no longer required to jump through various functions and manually manage the promise with resolve() and reject() calls.

Type safety is also improved by adding proper type definitions to all the affected code.

Does this PR introduce a breaking change? No

Other information This is a cleanup, but also I am going through and selectively re-writing code to get more familiar with the code-base.

[coveralls]

Pull Request Test Coverage Report for Build 11821216180

Details

• 26 of 26 (100.0%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 100.0%

---

Totals
Change from base Build 11817735531:	0.0%
Covered Lines:	89
Relevant Lines:	89

---

💛 - Coveralls

[jonkoops]

Note this is just the beginning of the code cleanup, I'll be going through the code and refactoring it before releasing the new major so I have a better understanding of how the code works in case bugs arise.

[jonkoops]

@rolandjitsu this one is ready to be reviewed, can I ask you to take a look at it?

[jonkoops]

I see the coverage went down because the tests are not hitting a specific no-op case that did not exist before, let me add a test for that.

[jonkoops]

Ok, test added. Coverage is back at a 100%.

[jonkoops]

@rolandjitsu I agree that isFileSystemDirectoryEntry() and isFileSystemFileEntry() were too overzealous in naming so I've simplified them to isDirectoryEntry() and isFileEntry(), that should be plenty of information since they are always called in a context.