Provide a way to check if FSharpSymbolUse is resolved from id

[auduchinok]

When getting symbol uses via GetAllUsesOfAllSymbolsInFile() there're plenty of uses that were added implicitly or were resolved from syntax construction other than name use.
Examples:

• definition of optional parameter adds uses of OptionalParameterAttribute and its namespaces
• use of indexer property with .[ ... ]

May ItemOccurence type be extended with these cases?

module ClassLibrary32

type T() =
 member x.Opt(?p: int) = ()

[vasily-kirichenko]

The attribute is generated here https://github.com/Microsoft/visualfsharp/blob/c0b044c6c578fe281b689bcd93cffb9def24e967/src/fsharp/TypeChecker.fs#L989-L998 and at that point the information that it's synthesized is lost. So, we need to add a field to SynAttribute and a field to ItemOccurenece.Use. Let me try.

[vasily-kirichenko]

Huh. It's a complex task. @dsyme any tips how to better implement it?

[dsyme]

May ItemOccurence type be extended with these cases?

It's certainly OK to add this information. These might also come in handy:

 /// Synthetic marks ranges which are produced by intermediate compilation phases. This
 /// bit signifies that the range covers something that should not be visible to language
 /// service operations like dot-completion.
 member IsSynthetic : bool 
 member MakeSynthetic : unit -> range

[auduchinok]

Another example is shown in #3939 where one of the uses came from the range of a literal in code.