Refactor and improve colorization language services support (#4433)

* saving current progress

* Migrated to json, moved from directly in patterns to repository.

Using the cmake-language documentation
(https://cmake.org/cmake/help/latest/manual/cmake-language.7.html) and
the language grammars documentation
(https://macromates.com/manual/en/language_grammars) I've migrated to
json, as well as modify the 'name' fields to match names that have
common themes associated. I have it working but haven't figured out the
'string' pattern, something is messing up with that one

* fix the string pattern

Turns out, after investigating why the string pattern wasn't working,
negative lookbehinds, or any lookbehinds for that matter, aren't valid
in TextMate Grammars

* no need for the captures in the string pattern

* split booleans out of operators

Based on docs here:
https://cmake.org/cmake/help/latest/command/if.html#matches, many of the
operators should be broken out into specific booleans. I still need to
figure out how to get it to recognize that we shouldn't identify the
various properties, variables, etc, incorrectly

* missed \\ to escape properly when matching what we have in our former xml

* Add generator expression.

Based on this documentation:
https://cmake.org/cmake/help/latest/manual/cmake-generator-expressions.7.html.
The captures were necessary to capture the entire statement, otherwise
the matching didn't fully do what we wanted

* Add recursive generator expression

This ensures that nested generator expressions are matched correctly

* Add variable references as a pattern

Within generator expressions, it'd still be nice to match variable
references.

* committing a TODO for unquoted and escape sequences, won't work as is because of json comments not being supported

* Add unquoted

It's not fully working, doesn't match the first in the parameter list,
or the last, seems to miss some escaping characters, WIP

* Slightly modify the names of some, add unquoted

There is still more to do. I want to make this match more builtIn
variables and properties, and then PR, though there will still be more
work to make it fully implementing the spec

* add a couple built in variables

Author: gcampbell-msft

package.json

@@ -131,12 +131,12 @@
         {
             "language": "cmake",
             "scopeName": "source.cmake",
-            "path": "./syntaxes/CMake.tmLanguage"
+            "path": "./syntaxes/CMake.tmLanguage.json"
         },
         {
             "language": "cmake-cache",
             "scopeName": "source.cmakecache",
-            "path": "./syntaxes/CMakeCache.tmLanguage"
+            "path": "./syntaxes/CMakeCache.tmLanguage.json"
         }
     ],
     "commands": [