[vscode] support TelemetryLogger

[rschnekenbu]

What it does

Fixes #12232

Add Telemetry support for extensions.
This adds the TelemetryLogger API and some additional types related to the TelemetryLogger. Telemetry is still declared as not enabled, so it won't change anything to the current behavior. However, extensions relying on Telemetry API will be able to run without any issues. As soon as the Telemetry API will be declared as mature enough, it will be possible to enable it with the support of preferences or a command line parameter (to be decided later).
TelemetrySender has no implementation, as this is really depending on the needs and the infrastructure of the extensions. This is basically the same for vscode, where an implementation using Application Insights is provided as an additional module.

• IP Check Approved

Contributed on behalf of ST Microelectronics

How to test

Telemetry is still declared as not available according to: https://github.com/eclipsesource/theia/blob/bb71e70f6305b252aa5d663f0f73c1468b884821/packages/plugin-ext/src/plugin/telemetry-ext.ts#L20
So running the following actions won't produce anything until the flag is set to true.

1. Install telemetry-sample extension (forked from vscode extension samples) - source
2. Trigger the command Log Telemetry event. This will result on a notification on the test UI (directly displayed from the extension command before logging) and a log in the console if telemetry is activated. The log in the console is printed by the basic TelemetrySender provided in the sample. The logged data is cleaned as documented in the API (removal based on regex matching email, file path, Google key, etc.)
3. The same can be done with the command Log Telemetry Exception

Note: No output is currently produced in the telemetry output channel as it is described in the vscode API. Goal of this task was only to initiate the main implementation.

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

[rschnekenbu]

Thanks a lot for your review, @vince-fugnitto! I adressed most of the comments except the CQ one. I also rebased on the current master.

[JonasHelming]

@vince-fugnitto The CQ has been approved, is this PR good to go from your POV or do you have other comments?

[vince-fugnitto]

LGTM 👍

• the test plugin works as expected
• the code looks good, and feedback based on duplication from @theia/core has been addressed
• the CQ has been approved

[rschnekenbu]

Hi @vince-fugnitto, I rebased on latest master, and I fixed the 2 minor issues (missing new lines).