[Bug] Missing Yarn Dependency Check During Installation

[M-Arnone]

Describe the bug
When installing the Markdown Preview plugin, it does not check for the presence of Yarn. As a result, if Yarn is not installed, the plugin fails to work, but this failure is not immediately apparent.

To Reproduce
Steps to reproduce the behavior:

1. Install the Markdown Preview plugin without Yarn installed.
2. Attempt to use the plugin.
3. Notice that the plugin does not work due to the missing Yarn dependency.

Expected behavior
The installation process should check for the presence of Yarn. If Yarn is not installed, the user should be notified with a clear message indicating that Yarn is required for the plugin to function properly.

Screenshots
N/A (The issue is about the installation process and not a runtime error that can be captured in a screenshot).

Desktop (please complete the following information):

• OS: macOS Ventura 13.6.7 arm64
• Host: MacBook Air (M1, 2020)
• Kernel: Darwin 22.6.0
• Shell: bash 3.2.57

Log:

[Tweekism]

Hey mate,

Looks like this one isn't being maintained anymore or at least the owner has been out of contact with no commits or merged pull request for the last 9 months. So errors like this will start to undoubtedly creep in over time unless someone takes over the project or people switch to an alternative.

I'm detailing my search in #688