Support 'logUri' and 'extension' (partially) to PluginContext

[martin-fleck-at]

• Ensure 'logUri' and 'extension' property are present in context
• 'extension' currently has always theia.Plugin type, even in vscode

Fixes #10033

What it does

• Add support for 'logUri' and 'extension' property to the PluginContext

How to test

• I pushed a branch https://github.com/martin-fleck-at/theia/tree/issues/10033-test which adds a plugin to Theia that evaluates the Plugin context to produce error dialogs for missing properties such as:
  

Review checklist

• As an author, I have thoroughly tested my changes and carefully followed the review guidelines

Reminder for reviewers

• As a reviewer, I agree to behave in accordance with the review guidelines

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** To Note: ** This PR adds the 'extension' property but it is currently ALWAYS of type TheiaPlugin even if the plugin is a VS Code extension. There is already a conversion available in the VS Code package for the 'vscode.extensions.getExtension' API. However, I did not find the proper way to use that functionality in the plugin manager as it probably requires some RPC calls. So if someone could point me in the right direction, I could also have a look at this. Until then, the custom VS Code extension properties (extensionPath, extensionUri and extensionKind) are not available through the context. However, they are available if you get the extension through vscode.extensions.getExtension.

[colin-grant-work]

Could you clarify your question about the plugin type a bit? Am I correct that you'd like to use the asVsCodeExtension converter in the plugin-manager.ts file when you build the context for the plugin, if the plugin is in fact a VSCode plugin?

My inclination would be to just add the fields that asVsCodeExtension adds anyway, since they're unlikely to do any harm to a plugin that isn't expecting them, but perhaps others have better ideas.

[martin-fleck-at]

@colin-grant-work Thank you for your fast reply! Yes, exactly, the plugin manager also needs to be aware of the additional properties that were added to the Theia plugin so that it can also be used as a VSCode extension. Previously this was only done for the vscode API calls (vscode.extensions.all, vscode.extensions.getExtension) but we need the same conversion for the 'extension' property used in the PluginContext (or ExtensionContext in VSCode). As you suggested, I now simply moved the additional properties directly into the class so that it automatically covers all aspects of a Theia plugin and a VSCode extension. This also made the conversion within the vscode.extension.* calls unnecessary. With that everything seems to work for me:

[colin-grant-work]

This looks good to me and better satisfies the expectations of VSCode plugins.