[3party] Use relative URLs for submodules

Remove explicit dependency on GitHub.com

Signed-off-by: Roman Tsisyk <roman@tsisyk.com>

.gitmodules

@@ -1,67 +1,67 @@
 [submodule "tools/osmctools"]
   path = tools/osmctools
-  url = https://github.com/organicmaps/osmctools.git
+  url = ../osmctools.git
 [submodule "tools/kothic"]
   path = tools/kothic
-  url = https://github.com/organicmaps/kothic.git
+  url = ../kothic.git
 [submodule "3party/protobuf/protobuf"]
   path = 3party/protobuf/protobuf
-  url = https://github.com/organicmaps/protobuf.git
+  url = ../protobuf.git
 [submodule "3party/Vulkan-Headers"]
   path = 3party/Vulkan-Headers
-  url = https://github.com/KhronosGroup/Vulkan-Headers.git
+  url = ../Vulkan-Headers.git
 [submodule "3party/boost"]
   path = 3party/boost
-  url = https://github.com/boostorg/boost.git
+  url = ../boost.git
   branch = boost-1.76.0
   ignore = dirty
 [submodule "3party/just_gtfs"]
   path = 3party/just_gtfs
-  url = https://github.com/organicmaps/just_gtfs.git
+  url = ../just_gtfs.git
   branch = for-usage-as-submodule
 [submodule "3party/expat"]
   path = 3party/expat
-  url = https://github.com/libexpat/libexpat.git
+  url = ../libexpat.git
   branch = R_2_2_9
 [submodule "3party/glm"]
   path = 3party/glm
-  url = https://github.com/g-truc/glm.git
+  url = ../glm.git
 [submodule "3party/icu/icu"]
   path = 3party/icu/icu
-  url = https://github.com/unicode-org/icu.git
+  url = ../icu.git
 [submodule "3party/freetype/freetype"]
 	path = 3party/freetype/freetype
-	url = https://github.com/organicmaps/freetype.git
+	url = ../freetype.git
 [submodule "3party/googletest"]
 	path = 3party/googletest
-	url = https://github.com/google/googletest.git
+	url = ../googletest.git
 [submodule "3party/fast_double_parser"]
 	path = 3party/fast_double_parser
-	url = https://github.com/lemire/fast_double_parser.git
+	url = ../fast_double_parser.git
 [submodule "3party/pugixml/pugixml"]
 	path = 3party/pugixml/pugixml
-	url = https://github.com/zeux/pugixml.git
+	url = ../pugixml.git
 [submodule "3party/jansson/jansson"]
 	path = 3party/jansson/jansson
-	url = https://github.com/akheron/jansson.git
+	url = ../jansson.git
 [submodule "3party/gflags"]
 	path = 3party/gflags
-	url = https://github.com/gflags/gflags
+	url = ../gflags
 [submodule "3party/fast_obj"]
 	path = 3party/fast_obj
-	url = https://github.com/thisistherk/fast_obj
+	url = ../fast_obj
 [submodule "3party/harfbuzz/harfbuzz"]
 	path = 3party/harfbuzz/harfbuzz
-	url = https://github.com/harfbuzz/harfbuzz.git
+	url = ../harfbuzz.git
 [submodule "3party/utfcpp"]
 	path = 3party/utfcpp
-	url = https://github.com/nemtrif/utfcpp.git
+	url = ../utfcpp.git
 [submodule "3party/glfw"]
 	path = 3party/glfw
-	url = https://github.com/glfw/glfw.git
+	url = ../glfw.git
 [submodule "3party/CMake-MetalShaderSupport"]
 	path = 3party/CMake-MetalShaderSupport
-	url = https://github.com/dpogue/CMake-MetalShaderSupport.git
+	url = ../CMake-MetalShaderSupport.git
 [submodule "3party/imgui/imgui"]
 	path = 3party/imgui/imgui
-	url = https://github.com/ocornut/imgui
+	url = ../imgui.git