Move dotnet-watch into dotnet/sdk repo

[mkArtakMSFT]

The dotnet-watch tool has no runtime impact. To enable faster iteration and fixes we need to move it to the dotnet/sdk repo to be able to release it with SDK ship cycle.

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We're moving this issue to the Next sprint planning milestone for future evaluation / consideration. We will evaluate the request when we are planning the work for the next milestone. To learn more about what to expect next and how this issue will be handled you can read more about our triage process here.

[gfoidl]

@mkArtakMSFT can please update the typo in the issue-title?
I don't want to be pendantic (especially as my typing isn't the best sometimes), but while searching for issues here on GH it might not show up with the typo.