Support uppercase non-ascii characters in import assist, flyimport completion, and workspace symbol search

Currently import assist, flyimport completion, and workspace symbol search RA does not work for Symbols containing non-ascci uppercase characters.

rust-analyzer version: 0.3.3049-standalone

rustc version: rustc 1.98.0 (88d9e12ae 2026-08-18)

editor or extension: VSCode, rust-analyzer 0.3.3049

code snippet to reproduce:

struct Übung; // Try to import this in another module via Ctrl + . in the VSCodew extension

Current behavior:

Expected: