Add per-file-target-version option (#16257)

## Summary

This PR is another step in preparing to detect syntax errors in the
parser. It introduces the new `per-file-target-version` top-level
configuration option, which holds a mapping of compiled glob patterns to
Python versions. I intend to use the
`LinterSettings::resolve_target_version` method here to pass to the
parser:


f50849aeef/crates/ruff_linter/src/linter.rs (L491-L493)

## Test Plan

I added two new CLI tests to show that the `per-file-target-version` is
respected in both the formatter and the linter.

ruff.schema.json

@@ -578,6 +578,16 @@
         }
       }
     },
+    "per-file-target-version": {
+      "description": "A list of mappings from glob-style file pattern to Python version to use when checking the corresponding file(s).\n\nThis may be useful for overriding the global Python version settings in `target-version` or `requires-python` for a subset of files. For example, if you have a project with a minimum supported Python version of 3.9 but a subdirectory of developer scripts that want to use a newer feature like the `match` statement from Python 3.10, you can use `per-file-target-version` to specify `\"developer_scripts/*.py\" = \"py310\"`.\n\nThis setting is used by the linter to enforce any enabled version-specific lint rules, as well as by the formatter for any version-specific formatting options, such as parenthesizing context managers on Python 3.10+.",
+      "type": [
+        "object",
+        "null"
+      ],
+      "additionalProperties": {
+        "$ref": "#/definitions/PythonVersion"
+      }
+    },
     "preview": {
       "description": "Whether to enable preview mode. When preview mode is enabled, Ruff will use unstable rules, fixes, and formatting.",
       "type": [