[BugFix] Check if the current user has write access

[MateuszGuzek]

Description

Currently _is_writable check if any user or group can write to file. In practice, we want to chek if active user can do that. The simple fix should solve the issue, I tested it locally on a problematic file where owner could write to but group not. With the proposed changes, it works.

Motivation and Context

Why is this change required? What problem does it solve?
If it fixes an open issue, please link to the issue here.
You can use the syntax close #15213 if this solves the issue #15213

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• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds core functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation (update in the documentation)
• Example (update in the folder of examples)

Checklist

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• I have read the CONTRIBUTION guide (required)
• My change requires a change to the documentation.
• I have updated the tests accordingly (required for a bug fix or a new feature).
• I have updated the documentation accordingly.

[vmoens]

Sounds great! I wasn't sure about that, this one seems much cleaner