Document all capability atoms and profiles. about slang

[ArielG-NV]

Discussion from another issue about this topic:

@ArielG-NV , do we have a way to dump the name strings of profiles?
As far as I can see, there isn't a way to do it currently.

There currently is no way todo this.

Since there are a lot of profile names, I don't think we can list all of them on the document.
We should refer to a command-line option that can print out all the available profile name strings.

I believe we could do both options.

The idea I have in mind for documenting every capability/profile:

1. inside tools\slang-capability-generator\capability-generator-main.cpp we could add logic to require a /// comment above the line of a capability definition.
2. store this string inside slang\build\source\slang\capability\slang-generated-capability-defs-impl.h.
3. Add build step to Slang (or CI) to autogenerate a user-doc with all capabilities using slang\build\source\slang\capability\slang-generated-capability-defs-impl.h.
4. output the auto-generate code from '.3' as a a command-line output with slangc if slangc -help capabilities is added (or something similar)