Kernel: Remove all friend declarations from SysFSComponentRegistry

Let them access the class using public API instead.

Kernel/FileSystem/ProcFS.cpp

@@ -115,7 +115,7 @@ ProcFSInode::~ProcFSInode()
 }
 
 ProcFS::ProcFS()
-    : m_root_inode(ProcFSComponentsRegistrar::the().m_root_folder->to_inode(*this))
+    : m_root_inode(ProcFSComponentsRegistrar::the().root_folder().to_inode(*this))
 {
 }
 

Kernel/FileSystem/SysFS.cpp

@@ -42,7 +42,7 @@ NonnullRefPtr<SysFSRootFolder> SysFSRootFolder::create()
 
 KResult SysFSRootFolder::traverse_as_directory(unsigned fsid, Function<bool(FileSystem::DirectoryEntryView const&)> callback) const
 {
-    Locker locker(SysFSComponentRegistry::the().m_lock);
+    Locker locker(SysFSComponentRegistry::the().get_lock());
     callback({ ".", { fsid, component_index() }, 0 });
     callback({ "..", { fsid, 0 }, 0 });
 
@@ -64,7 +64,7 @@ NonnullRefPtr<SysFS> SysFS::create()
 }
 
 SysFS::SysFS()
-    : m_root_inode(SysFSComponentRegistry::the().m_root_folder->to_inode(*this))
+    : m_root_inode(SysFSComponentRegistry::the().root_folder().to_inode(*this))
 {
     Locker locker(m_lock);
 }

Kernel/FileSystem/SysFS.h

@@ -24,11 +24,6 @@ private:
 };
 
 class SysFSComponentRegistry {
-    friend class SysFS;
-    friend class SysFSComponent;
-    friend class SysFSDirectory;
-    friend class SysFSRootFolder;
-
 public:
     static SysFSComponentRegistry& the();
 
@@ -37,7 +32,8 @@ public:
     SysFSComponentRegistry();
     void register_new_component(SysFSComponent&);
 
-    NonnullRefPtr<SysFSDirectory> root_folder() { return m_root_folder; }
+    SysFSDirectory& root_folder() { return m_root_folder; }
+    Lock& get_lock() { return m_lock; }
 
 private:
     Lock m_lock;

Kernel/FileSystem/SysFSComponent.cpp

@@ -28,7 +28,7 @@ SysFSComponent::SysFSComponent(StringView name)
 
 KResult SysFSDirectory::traverse_as_directory(unsigned fsid, Function<bool(FileSystem::DirectoryEntryView const&)> callback) const
 {
-    Locker locker(SysFSComponentRegistry::the().m_lock);
+    Locker locker(SysFSComponentRegistry::the().get_lock());
     VERIFY(m_parent_folder);
     callback({ ".", { fsid, component_index() }, 0 });
     callback({ "..", { fsid, m_parent_folder->component_index() }, 0 });