[ty] Add support for PEP 750 t-strings (#20085)

This PR attempts to adds support for inferring`string.templatelib.Template` for t-string literals.

crates/ty_python_semantic/resources/mdtest/t_strings.md

@@ -0,0 +1,20 @@
+# Template strings
+
+(NB: `black` does not support Python 3.14 at the time of this writing)
+
+<!-- blacken-docs:off -->
+
+```toml
+[environment]
+python-version = "3.14"
+```
+
+Template strings, or t-strings, were added in Python 3.14.
+
+They may be specified as literals and are objects of type `string.templatelib.Template`.
+
+## Empty template string
+
+```py
+reveal_type(t"")  # revealed: Template
+```