Consider to rename resourceIdentityService

[bpasero]

While looking into lifting services we declare in src/vs/platform to src/vs/workbench because they are only used there, I came across resourceIdentityService (which I moved to workbench btw: c57b7cd).

Since we already have a IURIIdentityService (probably came in later), I suggest to rename this service to better reflect it's purpose if possible.

Looking at the implementation it seems to produce a hash of the resource, so maybe IResourceHashService or IURIHashService?

[sandy081]

Removed this service and inline it in main as it is not needed anywhere at present.