Class TheiaHeadlessPluginScanner

Adapt the given plugin's metadata for headless deployment, where it does not already natively specify its headless deployment, such as is the case for plugins declaring the "vscode" or "theiaPlugin" engine. This consists of cloning the relevant properties of its deployment metadata and modifying them as required, including but not limited to:

• renaming the lifecycle start and stop functions as 'activate' and 'deactivate' following the VS Code naming convention (in case the plugin is a Theia-style plugin that uses 'start' and 'stop')
• deleting inapplicable information such as frontend and backend init script paths
• filtering/rewriting contributions and/or activation events

The cloning is necessary to retain the original information for the non-headless deployments that the plugin also supports.