Add a button to VS Code Ports View that adds the port to .gitpod.yml in case it's missing there

[felladrin]

Add a button to VS Code Ports View that adds the port to .gitpod.yml in case it's missing there.

For cases when ports are decided during the development, or when we notice a third-party service is using some port and we want to set its 'onOpen' behavior to 'ignore', for example.

There could be another button, along with the four that already exist, to add it to .gitpod.yml.
Displaying the button as 'disabled' when the port is already listed in .gitpod.yml would also help to spot missing ports.

Here's a screenshot of what the Ports View looks like at this moment:

[loujaybee]

Copying internal comment from discussion:

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We indeed should probably think about the “drift” of a users configurations when in a workspace more generally, e.g.

• When user installs tools
• When user installs extensions
• When user copies secrets

As these can all be “lost” when the user starts a new ephemeral workspace and adds friction. We should where we can “nudge” users towards codifying these settings in the YAML when they take manual actions. Maybe for ports this view is the right touchpoint. (edited)