This CL adds support for all kinds of Types to "textDocument/symbol"
requests. While LSP has support for classes and structs, it does not
have support for generic types. Only classes are marked as such,
while all other types are marked as structs in terms of the LSP.

Special care has to be taken with TypeAliases. Generic call sites
introduce a new scope (similar to namespace scopes), where new
TypeAliases are created for Generic type arguments. These TypeAliases
then point to the specialized type inside this call-site specific
scope. To omit the specialized TypeAliaes from the symbols list,
they are marked using the "is_user_defined" flag.

R=sigurds@chromium.org

Bug: v8:8880
Change-Id: I576d1c677a5255d54f7774aa053f431608a4cd0c
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1613240
Commit-Queue: Sigurd Schneider <sigurds@chromium.org>
Reviewed-by: Sigurd Schneider <sigurds@chromium.org>
Auto-Submit: Simon Zünd <szuend@chromium.org>
Cr-Commit-Position: refs/heads/master@{#61534}