SenseApis: New senseApiManager and X11XcbApi

Still fleshing these out but ultimately senseApiMgr will manage
sense apis, and the X11XcbApi is where we'll connect to Xcb and
read the screen.

hcore/include/senseApis/senseApiManager.h

@@ -0,0 +1,69 @@
+#ifndef SENSE_API_MANAGER_H
+#define SENSE_API_MANAGER_H
+
+#include <config.h>
+#include <memory>
+#include <vector>
+#include <string>
+#include <optional>
+#include <functional>
+
+struct SenseApiInstance {
+    int a;
+
+    bool operator==(const SenseApiInstance& other) const {
+        return a == other.a;
+    }
+};
+
+class SenseApiLib {
+public:
+    std::string libraryPath;
+    std::unique_ptr<void, decltype(&dlclose)> handle;
+
+    SenseApiLib(const std::string& path)
+        : libraryPath(path), handle(nullptr, &dlclose) {}
+};
+
+class SenseApiManager {
+public:
+    static SenseApiManager& getInstance()
+    {
+        static SenseApiManager instance
+        {
+#ifdef CONFIG_SENSEAPI_FOO
+            "builtinApi1",
+#endif
+#ifdef CONFIG_SENSEAPI_BAR
+            "builtinApi2",
+#endif
+            // X11 XCB is always built-in.
+            "x11-xcb"
+        };
+
+        return instance;
+    }
+
+    void registerSenseApi(const SenseApiInstance& apiInstance);
+    void unregisterSenseApi(const SenseApiInstance& apiInstance);
+
+    SenseApiLib& loadSenseApiLib(const std::string& libraryPath);
+    std::optional<std::reference_wrapper<SenseApiLib>> getSenseApiLib(
+        const std::string& libraryPath);
+    void unloadSenseApiLib(const std::string& libraryPath);
+
+private:
+    SenseApiManager() = delete;
+    SenseApiManager(std::initializer_list<std::string> builtinApis)
+        : builtinSenseApis(builtinApis) {}
+    ~SenseApiManager() = default;
+
+    SenseApiManager(const SenseApiManager&) = delete;
+    SenseApiManager& operator=(const SenseApiManager&) = delete;
+
+    std::vector<std::unique_ptr<SenseApiInstance>> senseApiInstances;
+    std::vector<std::unique_ptr<SenseApiLib>> senseApiLibs;
+    const std::vector<std::string> builtinSenseApis;
+};
+
+#endif // SENSE_API_MANAGER_H