NSURLSession rewrite (#422)

* clang-format: Do not use tabs

* Ignore clangd cache and compile_commands

* NSBlockOperation: Fix memory leak

* NSHTTPCookie: Fix expires date parsing

* NSHTTPCookie: Release DateFormatter after use

* NSOperation: Remove all objects at end of execution

* Reimplementation of NSURLSession

* NSURLSession: Update expiration dates in test

* Update ChangeLog

* Fix trivial compiler warning caused by missing import

* Import GSDispatch.h for definition of DISPATCH_QUEUE_SERIAL

* Import common.h early to avoid header conflict

* Fix import order to avoid conflicts and ensure we have correct localisation macro

* Check for presence of dispatch_cancel

* Cancel timer using dispatch_source_cancel() if dispatch_cancel() is missing.

* NSURLSession: Replace dispatch_io with dispatch_source in unit test HTTP server

---------

Co-authored-by: hmelder <service@hugomelder.com>

Source/NSURLRequest.m

@@ -39,6 +39,7 @@ typedef struct {
   NSMutableDictionary		*headers;
   BOOL				shouldHandleCookies;
   BOOL                          debug;
+  BOOL        assumesHTTP3Capable;
   id<GSLogDelegate>             ioDelegate;
   NSURL				*URL;
   NSURL				*mainDocumentURL;
@@ -56,6 +57,9 @@ typedef struct {
 @interface	_GSMutableInsensitiveDictionary : NSMutableDictionary
 @end
 
+@interface	_GSInsensitiveDictionary : NSMutableDictionary
+@end
+
 @implementation	NSURLRequest
 
 + (id) allocWithZone: (NSZone*)z
@@ -116,6 +120,7 @@ typedef struct {
 	  ASSIGN(inst->bodyStream, this->bodyStream);
 	  ASSIGN(inst->method, this->method);
 	  inst->shouldHandleCookies = this->shouldHandleCookies;
+    inst->assumesHTTP3Capable = this->assumesHTTP3Capable;
 	  inst->debug = this->debug;
 	  inst->ioDelegate = this->ioDelegate;
 	  inst->headers = [this->headers mutableCopy];
@@ -375,6 +380,11 @@ typedef struct {
   return [this->headers objectForKey: field];
 }
 
+- (BOOL) assumesHTTP3Capable
+{
+  return this->assumesHTTP3Capable;
+}
+
 @end
 
 
@@ -454,6 +464,11 @@ typedef struct {
     }
 }
 
+- (void)setAssumesHTTP3Capable:(BOOL)capable
+{
+  this->assumesHTTP3Capable = capable;
+}
+
 @end
 
 @implementation	NSURLRequest (Private)
@@ -468,6 +483,11 @@ typedef struct {
   return this->ioDelegate;
 }
 
+- (NSDictionary *) _insensitiveHeaders
+{
+  return [this->headers copy];
+}
+
 - (id) _propertyForKey: (NSString*)key
 {
   return [this->properties objectForKey: key];