[code] streamline terminal integration

[akosyakov]

We spent a lot of time in the past to align our terminal implementation to work again supervisor instead we would like to use the default implementation from web-server. The following steps:

• remove our implementation and hook in web-server implementation
• move task terminals from gitpod-remote to gitpod-shared and enable for both remote and web targets
• there was a new proposed terminal API which allow to layout them, we should make use of it to layout task terminals properly.

[akosyakov]

/schedule

[roboquat]

@akosyakov: Issue scheduled in the IDE team (WIP: 0)

In response to this:

/schedule

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