Bring oxen-encoding back in as a submodule

As long as it's loaded before oxen-mq or libquic, this should end up
being the one that gets used in oxen-mq/libquic, and so we don't have to
update those when we want something in a newer oxen-encoding.

.gitmodules

@@ -35,3 +35,6 @@
 [submodule "external/span-lite"]
 	path = external/span-lite
 	url = https://github.com/martinmoene/span-lite.git
+[submodule "external/oxen-encoding"]
+	path = external/oxen-encoding
+	url = https://github.com/oxen-io/oxen-encoding.git

external/CMakeLists.txt

@@ -26,7 +26,9 @@ if(SUBMODULE_CHECK)
     message(STATUS "Checking submodules")
     check_submodule(CLI11)
     check_submodule(cpr)
+    check_submodule(ghc-filesystem)
     check_submodule(nlohmann)
+    check_submodule(oxen-encoding)
     check_submodule(oxen-libquic)
     check_submodule(oxen-mq)
     check_submodule(pybind11)
@@ -58,6 +60,7 @@ macro(system_or_submodule BIGNAME smallname pkgconf subdir)
   endif()
 endmacro()
 
+system_or_submodule(OXENC oxenc liboxenc>=1.0.10 oxen-encoding)
 system_or_submodule(OXENMQ oxenmq liboxenmq>=1.2.14 oxen-mq)
 
 set(JSON_BuildTests OFF CACHE INTERNAL "")

external/oxen-encoding

@@ -0,0 +1 @@
+Subproject commit a7de63756dcc5c31cb899a4b810e6434b1a7c01c