initial support for working together with language-server

[daimor]

This PR fixes #

[gjsjohnmurray]

With both extension installed and active, if I disable the LS extension it requires a reload. Things then work as expected, with the ObjectScript extension taking over all the roles. But if I subsequently enable LS no reload is required and we get contributions from both extensions (e.g. double hovers).

Here's an idea for a solution:

• During activate gather the Disposables returned from each of the onXXX and registerXXX calls that you make only when LS isn't active.
• Use the extensions.odDidChange event to detect when LS gets activated. When this happens, dispose of all the Disposables you gathered during activation.

[daimor]

With both extension installed and active, if I disable the LS extension it requires a reload. Things then work as expected, with the ObjectScript extension taking over all the roles. But if I subsequently enable LS no reload is required and we get contributions from both extensions (e.g. double hovers).

Here's an idea for a solution:

• During activate gather the Disposables returned from each of the onXXX and registerXXX calls that you make only when LS isn't active.
• Use the extensions.odDidChange event to detect when LS gets activated. When this happens, dispose of all the Disposables you gathered during activation.

Done

[gjsjohnmurray]

LGTM and I will merge it immediately.