Implement template strings (#17851)

This PR implements template strings (t-strings) in the parser and
formatter for Ruff.

Minimal changes necessary to compile were made in other parts of the code (e.g. ty, the linter, etc.). These will be covered properly in follow-up PRs.

crates/ruff_python_parser/resources/valid/expressions/t_string.py

@@ -0,0 +1,74 @@
+# Empty t-strings
+t""
+t""
+t''
+t""""""
+t''''''
+
+t"{" t"}"
+t"{foo!s}"
+t"{3,}"
+t"{3!=4:}"
+t'{3:{"}"}>10}'
+t'{3:{"{"}>10}'
+t"{  foo =  }"
+t"{  foo =  :.3f  }"
+t"{  foo =  !s  }"
+t"{  1, 2  =  }"
+t'{t"{3.1415=:.1f}":*^20}'
+
+{"foo " t"bar {x + y} " "baz": 10}
+match foo:
+    case "one":
+        pass
+    case "implicitly " "concatenated":
+        pass
+
+t"\{foo}\{bar:\}"
+t"\\{{foo\\}}"
+t"""{
+    foo:x
+        y
+        z
+}"""
+t"{ (  foo )  = }"
+
+t"normal {foo} {{another}} {bar} {{{three}}}"
+t"normal {foo!a} {bar!s} {baz!r} {foobar}"
+t"normal {x:y + 2}"
+t"{x:{{1}.pop()}}"
+t"{(lambda x:{x})}"
+t"{x =}"
+t"{    x = }"
+t"{x=!a}"
+t"{x:.3f!r =}"
+t"{x = !r :.3f}"
+t"{x:.3f=!r}"
+"hello" t"{x}"
+t"{x}" t"{y}"
+t"{x}" "world"
+t"Invalid args in command: {command, *args}"
+"foo" t"{x}" "bar"
+(
+    t"a"
+    t"b"
+    "c"
+    rt"d"
+    fr"e"
+)
+
+# With unicode strings
+u"foo" t"{bar}" "baz" " some"
+"foo" t"{bar}" u"baz" " some"
+"foo" t"{bar}" "baz" u" some"
+u"foo" t"bar {baz} really" u"bar" "no"
+
+
+# With f-strings
+f"{this}" t"{that}"
+t"{this}"f"{that}"
+t"{this}" "that" f"{other}"
+f"one {this} two" "that" t"three {other} four"
+
+# Nesting
+t"{f"{t"{this}"}"}"