implemented quantized-gemma3 (#2902)

* implemented quantized-gemma, inference not working

* Fixed a few modeling bugs: outputing the correct tokens for a few iterations then garbage

* lint

* clippy

* quantized-gemma3 example working

* added readme

* clippy

candle-examples/examples/quantized-gemma/README.md

@@ -0,0 +1,18 @@
+# candle-quantized-gemma
+
+Candle implementation of quantized Gemma.
+
+## Running an example
+
+```bash
+$ cargo run --example quantized-gemma -- --prompt "Write a function to calculate fibonacci numbers. "
+
+> ```python
+> def fibonacci(n):
+>     """Calculates the nth Fibonacci number using recursion."""
+>     if n <= 1:
+>         return n
+>     else:
+>         return fibonacci(n-1) + fibonacci(n-2
+> ```
+```