Epic: SSH key support for VS Code Desktop

[loujaybee]

Context	Integrate SSH Gateway into VS Code Desktop to bring Gitpod users a more stable and reliable desktop experience .
Owner	Product - @loujaybee / Tech - @akosyakov
Value	More stable connections, no longer a reliance on local companion process or generated keys
Acceptance Criteria	- Current SSH method is removed from VS Code and replaced with SSH Gateway - No impact on users on self-hosted who require the current SSH implementation
Growth Area	Activation & Retention / Expansion
Persona(s)	N/A
Hypothesis	Implementing the new SSH method will lead to a more reliable SSH approach in VS Code.
Measurement	N/A
In scope	N/A
Out of scope	- Any workspace management from VS Code (e.g. creating / updating workspaces)
Complexities
Latest Update	04.05.2022 - Descoped API's (moved to issue: #9757) and reduced to SSH Gateway within scope. Work has now started.

Related issues:

• Gitpod Remote extension overrides remote.SSH.configFile setting #5889
• [code-desktop] stop the local app when uninstalling extension #6127
• Unprotected private key file #6615
• Allow for automatic SSH trust #9619