Fix relative file paths with fragments

[codeclown]

What does this PR do?

Fixes fragments when schema URL is a local file.

Example of such a reference:

# yaml-language-server: $schema=../../schemas/example.schema.json#/definitions/CustomSpec

Currently this doesn't work in VS Code:

Error on hover is:

Unable to load schema from '/path/to/schemas/example.schema.json#/definitions/CustomSpec': No content.YAML(768)

The issue is caused by "#" being turned into "%23" during some path resolve operations. This PR fixes it by excluding the fragment during those operations.

What issues does this PR fix or reference?

Couldn't find a GitHub issue.
Relates somewhat to old PR which added fragment support: #530

Is it tested? How?

Includes automated test in existing suite.
I don't know how to test this with VS Code directly (if you could advice, I'll happily test locally; as a sidenote, CONTRIBUTING.md in this regard would be helpful).

[coveralls]

Coverage increased (+0.04%) to 78.649% when pulling e93cab7 on codeclown:fix-local-file-fragments into 5bafa9d on redhat-developer:main.

[evidolob]

@codeclown Thx for contribution.
To test this in vscode you can follow https://github.com/redhat-developer/vscode-yaml/blob/main/CONTRIBUTING.md

[codeclown]

@evidolob Thanks for the tip! I managed to test the change locally, and it works as expected.

Also added an if-else to the test to account for Windows paths.