fix: prevent pluginloader.js from removing globally installed packages

[SARTHAK2427]

Description

This PR fixes an issue where the CLI unintentionally removed globally installed npm packages during plugin removal

The current implementation uses npm rm -g, which removes packages from the global environment instead of limiting the operation to the CLI or project scope. This leads to unintended system-wide deletions. During testing, a globally installed package was removed after running the plugin removal command

Fixes #403

Changes

• Replaced the global uninstall command (npm rm -g) with a safer alternative to prevent unintended removal of globally installed packages.

npm unlink ${pluginName}

• Added Existence Validation: Implemented a check to verify the plugin exists before removal. If a plugin is missing, the CLI now provides a clean neu: ERRR Unable to find plugin error instead of a stack trace crash

if (!plugins.includes(pluginName)) {
    utils.error(`Unable to find plugin: ${pluginName}`);
    process.exit(1);
}

if (isPluginInstalled(pluginName)) {
    await execAsync(`npm unlink ${pluginName}`);
}

[SARTHAK2427]

@shalithasuranga please review this pr