Don't await plugin deployment in backend process

[tortmayr]

What it does

• Don't await initialize method in PluginDeployerContribution sync to continue with backend loading while plugins are deployed
• Fix wrong performance measurements of resolvePlugins & deployPlugins & in PluginDeployerImpl
• Improve performance logging in HostedPluginSupport by only logging relevant measurements of sync/load and start plugins (i.e. if the plugin count is 0 just stop the measurement but don`t log)
• Update I18nPreloadContribution to ensure that we only load the localizations from the back end if the current locale is not equal to the default locale. This fixes an issue where we unnecessarily queried the localization server in the preload step if the locale is explicitly set to "en". (This happens for instance if you change the display language and then switch back to english).

Contributed on behalf of ST Microelectronics

How to test

Everything should work as before. In the example apps the deploy plugin step does not take very long because most of the
default plugins are rather minimal and can deployed very fast.
To see a the real benefit you could add a timeout to the PluginDeployerImpl to simulate a longer plugin deploy process:

    protected async doStart(): Promise<void> {
            await new Promise(resolve => setTimeout(resolve, 3500));
            ...
    }

On the current master the backend process will block and not start the frontend loading until the pluginDeployer is finished.
With this change the fronted is started and loaded right away. Once the plugins are deployed the frontend will be notified and
starts the plugins.

Follow-ups

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

[msujew]

Looks good to me 👍