Symbols in Current Document locator filter issues with clangd

Example: session.cpp in Qt Creator sources.

• Every entry seems to be split into multiple items, one labeled with only the class name, one labeled only with the function name
• All kinds of things are included, even calls to functions within the code and function pointers that are used in the code. The locator filter should only contain declarations/definitions. Probably also not declarations of local variables in functions.
• The items for functions should contain the function parameters (e.g. for distinguishing overloads)