LogManager: implement system module, client api, logging api (#1617)

Some notes:

* Unless `atmosphere!enable_log_manager` is true, Nintendo's log manager will be used instead.
  * This prevents paying memory costs for LM when not enabling logging.
  * To facilitate this, Atmosphere's log manager has a different program id from Nintendo's.
  * `atmosphere!enable_htc` implies `atmosphere!enable_log_manager`.
* LogManager logs to tma, and the SD card (if `lm!enable_sd_card_logging` is true, which it is by default).
* Binary logs are saved to `lm!sd_card_log_output_directory`, which is `atmosphere/binlogs` by default.

libraries/libstratosphere/source/lm/lm_remote_log_service.hpp

@@ -0,0 +1,63 @@
+/*
+ * Copyright (c) 2018-2020 Atmosphère-NX
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+#pragma once
+#include <stratosphere.hpp>
+#include "sf/lm_i_log_service.hpp"
+
+namespace ams::lm {
+
+    /* TODO: Real libnx primitives? */
+
+    #define NX_SERVICE_ASSUME_NON_DOMAIN
+
+    class RemoteLogger {
+        private:
+            ::Service m_srv;
+        public:
+            RemoteLogger(::Service &s) : m_srv(s) { /* ... */ }
+            ~RemoteLogger() { ::serviceClose(std::addressof(m_srv)); }
+        public:
+            /* Actual commands. */
+            Result Log(const sf::InAutoSelectBuffer &message) {
+                return serviceDispatch(&m_srv, 0,
+                    .buffer_attrs = { SfBufferAttr_In | SfBufferAttr_HipcAutoSelect },
+                    .buffers = { { message.GetPointer(), message.GetSize() } },
+                );
+            }
+
+            Result SetDestination(u32 destination) {
+                return serviceDispatchIn(&m_srv, 1, destination);
+            }
+    };
+    static_assert(lm::IsILogger<RemoteLogger>);
+
+    class RemoteLogService {
+        private:
+            ::Service m_srv;
+        public:
+            RemoteLogService(::Service &s) : m_srv(s) { /* ... */ }
+            ~RemoteLogService() { ::serviceClose(std::addressof(m_srv)); }
+        public:
+            /* Actual commands. */
+            Result OpenLogger(sf::Out<sf::SharedPointer<::ams::lm::ILogger>> out, const sf::ClientProcessId &client_process_id);
+    };
+    static_assert(lm::IsILogService<RemoteLogService>);
+
+    #undef NX_SERVICE_ASSUME_NON_DOMAIN
+
+    sf::SharedPointer<ILogService> CreateLogService();
+
+}