[feat] path.relative API method

[frankolson]

Describe the problem

I'm working with a couple projects where using the Tauri API to get the relative path between two files would be useful.

Describe the solution you'd like

I would like to update the Tauri commands and JS APIs to export a relative method/function similar to the one provided by the Node.js path module:

import { relative } from '@tauri/api/path';

// POSIX
relative('/data/orandea/test/aaa', '/data/orandea/impl/bbb') == '../../impl/bbb';

// Windows
relative('C:\\orandea\\test\\aaa', 'C:\\orandea\\impl\\bbb') == '..\\..\\impl\\bbb';

Alternatives considered

Create a custom Tauri command in each project.

Additional context

Originally discussed in #8270, posted by Natejoestev back on November 20, 2023

[frankolson]

I'm willing to create a PR for this work, but wanted to submit an issue first per the Pull Request Guidelines in the Tauri Contribution Guide

[amrbashir]

apologies for the late reply @frankolson, feel free to open a PR, thanks