ports: Add jsoncpp.

The build demands it but it's missing.
Copy from upstream vcpkg repo.

Fixes the following error:
```
Computing installation plan...
error: while looking for jsoncpp:x64-linux:
overte-files/vcpkg/cfe0a2a0/ports/jsoncpp: error: jsoncpp does not exist
```

cmake/ports/jsoncpp/portfile.cmake

@@ -0,0 +1,34 @@
+vcpkg_from_github(
+    OUT_SOURCE_PATH SOURCE_PATH
+    REPO open-source-parsers/jsoncpp
+    REF "${VERSION}"
+    SHA512 1d06e044759b1e1a4cc4960189dd7e001a0a4389d7239a6d59295af995a553518e4e0337b4b4b817e70da5d9731a4c98655af90791b6287870b5ff8d73ad8873
+    HEAD_REF master
+)
+
+string(COMPARE EQUAL "${VCPKG_LIBRARY_LINKAGE}" "static" JSONCPP_STATIC)
+string(COMPARE EQUAL "${VCPKG_CRT_LINKAGE}" "static" STATIC_CRT)
+
+vcpkg_cmake_configure(
+    SOURCE_PATH "${SOURCE_PATH}"
+    OPTIONS 
+        -DJSONCPP_WITH_CMAKE_PACKAGE=ON
+        -DBUILD_STATIC_LIBS=${JSONCPP_STATIC}
+        -DJSONCPP_STATIC_WINDOWS_RUNTIME=${STATIC_CRT}
+        -DJSONCPP_WITH_PKGCONFIG_SUPPORT=ON
+        -DJSONCPP_WITH_POST_BUILD_UNITTEST=OFF
+        -DJSONCPP_WITH_TESTS=OFF
+        -DJSONCPP_WITH_EXAMPLE=OFF
+        -DBUILD_OBJECT_LIBS=OFF
+)
+
+vcpkg_cmake_install()
+
+vcpkg_cmake_config_fixup(CONFIG_PATH lib/cmake/jsoncpp)
+
+file(REMOVE_RECURSE "${CURRENT_PACKAGES_DIR}/debug/include")
+
+vcpkg_copy_pdbs()
+vcpkg_fixup_pkgconfig()
+
+vcpkg_install_copyright(FILE_LIST "${SOURCE_PATH}/LICENSE")

cmake/ports/jsoncpp/vcpkg.json

@@ -0,0 +1,18 @@
+{
+  "name": "jsoncpp",
+  "version": "1.9.5",
+  "port-version": 4,
+  "description": "JsonCpp is a C++ library that allows manipulating JSON values, including serialization and deserialization to and from strings. It can also preserve existing comment in unserialization/serialization steps, making it a convenient format to store user input files.",
+  "homepage": "https://github.com/open-source-parsers/jsoncpp",
+  "license": "MIT",
+  "dependencies": [
+    {
+      "name": "vcpkg-cmake",
+      "host": true
+    },
+    {
+      "name": "vcpkg-cmake-config",
+      "host": true
+    }
+  ]
+}