common: refactor common library pt2 (#8588)

- remove common lib
- split settings, remove common-md
- move ipc interop/kb_layout to interop
- rename core -> settings, settings -> old_settings
- os-detect header-only; interop -> PowerToysInterop
- split notifications, move single-use headers where they're used
- winstore lib
- rename com utils
- rename Updating and Telemetry projects
- rename core -> settings-ui and remove examples folder
- rename settings-ui folder + consisent common/version include

src/common/utils/timeutil.h

@@ -0,0 +1,57 @@
+#pragma once
+
+#include <ctime>
+#include <cinttypes>
+#include <string>
+#include <optional>
+
+#include <winrt/base.h>
+
+namespace timeutil
+{
+    inline std::wstring to_string(const time_t time)
+    {
+        return std::to_wstring(static_cast<uint64_t>(time));
+    }
+
+    inline std::optional<std::time_t> from_string(const std::wstring& s)
+    {
+        try
+        {
+            uint64_t i = std::stoull(s);
+            return static_cast<std::time_t>(i);
+        }
+        catch (...)
+        {
+            return std::nullopt;
+        }
+    }
+
+    inline std::time_t now()
+    {
+        return winrt::clock::to_time_t(winrt::clock::now());
+    }
+
+    namespace diff
+    {
+        inline int64_t in_seconds(const std::time_t to, const std::time_t from)
+        {
+            return static_cast<int64_t>(std::difftime(to, from));
+        }
+
+        inline int64_t in_minutes(const std::time_t to, const std::time_t from)
+        {
+            return static_cast<int64_t>(std::difftime(to, from) / 60);
+        }
+
+        inline int64_t in_hours(const std::time_t to, const std::time_t from)
+        {
+            return static_cast<int64_t>(std::difftime(to, from) / 3600);
+        }
+
+        inline int64_t in_days(const std::time_t to, const std::time_t from)
+        {
+            return static_cast<int64_t>(std::difftime(to, from) / (3600 * (int64_t)24));
+        }
+    }
+}