Fix Windows URI construction bug causing ENOENT errors in workspace-s…

[alexmadPDE]

Problem

Fixes workspace MCP configuration on Windows for JetBrains IDEs.

Types of changes

• [X ] Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)

Description

Workspace-scoped MCP configuration fails on Windows with:
ENOENT: no such file or directory, mkdir 'C:\Program Files\JetBrains\PyCharm\file:\C:\Users...\workspace.amazonq\agents'

Bug:
Workspace scoped MCP configuration fail under Windows #7774
aws/aws-toolkit-vscode#7774

Root Cause

Manual URI construction in LspEditorUtil.toUri() creates malformed URIs on Windows that get interpreted as literal file paths.

Solution

• Replace manual URI construction with Path.toUri()
• Ensures proper cross-platform URI handling
• Eliminates malformed path issues

Checklist

• My code follows the code style of this project
• [New guy Need help with this ] I have added tests to cover my changes
• A short description of the change has been added to the CHANGELOG if the change is customer-facing in the IDE.
• I have added metrics for my changes (if required)

License

I confirm that my contribution is made under the terms of the Apache 2.0 license.