Add rfc9110 status code texts

Implement updated wording from RFC9110 for status code constants.

We keep the old constants around and map them to the new wording for
backwards compatibility

httpx/_status_codes.py

@@ -10,12 +10,12 @@ class codes(IntEnum):
 
     Status codes from the following RFCs are all observed:
 
-        * RFC 7231: Hypertext Transfer Protocol (HTTP/1.1), obsoletes 2616
+        * RFC 9110: HTTP Semantics
+           obsoletes 7231, which obsoletes 2616. Obsoletes 7238
         * RFC 6585: Additional HTTP Status Codes
         * RFC 3229: Delta encoding in HTTP
         * RFC 4918: HTTP Extensions for WebDAV, obsoletes 2518
         * RFC 5842: Binding Extensions to WebDAV
-        * RFC 7238: Permanent Redirect
         * RFC 2295: Transparent Content Negotiation in HTTP
         * RFC 2774: An HTTP Extension Framework
         * RFC 7540: Hypertext Transfer Protocol Version 2 (HTTP/2)
@@ -126,14 +126,14 @@ def is_error(cls, value: int) -> bool:
     GONE = 410, "Gone"
     LENGTH_REQUIRED = 411, "Length Required"
     PRECONDITION_FAILED = 412, "Precondition Failed"
-    REQUEST_ENTITY_TOO_LARGE = 413, "Request Entity Too Large"
-    REQUEST_URI_TOO_LONG = 414, "Request-URI Too Long"
+    CONTENT_TOO_LARGE = 413, "Content Too Large"
+    URI_TOO_LONG = 414, "URI Too Long"
     UNSUPPORTED_MEDIA_TYPE = 415, "Unsupported Media Type"
-    REQUESTED_RANGE_NOT_SATISFIABLE = 416, "Requested Range Not Satisfiable"
+    RANGE_NOT_SATISFIABLE = 416, "Range Not Satisfiable"
     EXPECTATION_FAILED = 417, "Expectation Failed"
     IM_A_TEAPOT = 418, "I'm a teapot"
     MISDIRECTED_REQUEST = 421, "Misdirected Request"
-    UNPROCESSABLE_ENTITY = 422, "Unprocessable Entity"
+    UNPROCESSABLE_CONTENT = 422, "Unprocessable Content"
     LOCKED = 423, "Locked"
     FAILED_DEPENDENCY = 424, "Failed Dependency"
     TOO_EARLY = 425, "Too Early"
@@ -156,6 +156,11 @@ def is_error(cls, value: int) -> bool:
     NOT_EXTENDED = 510, "Not Extended"
     NETWORK_AUTHENTICATION_REQUIRED = 511, "Network Authentication Required"
 
+    # for backwards compatibility, keep the old constants around
+    REQUEST_ENTITY_TOO_LARGE = CONTENT_TOO_LARGE
+    REQUEST_URI_TOO_LONG = URI_TOO_LONG
+    REQUESTED_RANGE_NOT_SATISFIABLE = RANGE_NOT_SATISFIABLE
+    UNPROCESSABLE_ENTITY = UNPROCESSABLE_CONTENT
 
 # Include lower-case styles for `requests` compatibility.
 for code in codes: