Consider using an existing library for variable replacement to support multi-root workspaces

[smac89]

Is your feature request related to a problem? Please describe.

The extension currently doesn't work well with multi-root workspaces due to being unable to understand the variables used to describe the path to a project root.

Describe the solution you'd like

Consider using https://github.com/DominicVonk/vscode-variables to replace the current replaceVars function, as it is able to resolve the correct paths for many of the existing variables.

Describe alternatives you've considered

No response

Additional context

This will make the plugin more robust and may also bring the following issues closer to being resolved:

• Support for multiple xmake projects in a workspace #160
• 当workspace里面有多个目录的时候，不能够自动检测目录，打开xmake文件也不能自动激活 #242

[waruqi]

I haven't had time to improve it recently, you can try it and open a pr.

[smac89]

@waruqi #287