feat: add 'vol' command

kernel/src/Fs/Boot.cpp

@@ -67,6 +67,7 @@ namespace Fs {
         int RdMkdir(void*, const char* p) { return Ramdisk::Mkdir(p); }
         int RdRename(void*, const char* o, const char* n) { return Ramdisk::Rename(o, n); }
         const char* RdGetLabel(void*) { return Ramdisk::GetLabel(); }
+        const char* RdGetFsType(void*) { return "ramdisk"; }
         int RdReadDirAt(void*, const char* p, const char** o, int m, int s) { return Ramdisk::ReadDirAt(p, o, m, s); }
 
         int RdStat(void*, const char* p, Vfs::StatInfo* out) {
@@ -99,6 +100,7 @@ namespace Fs {
             .Mkdir     = RdMkdir,
             .Rename    = RdRename,
             .GetLabel  = RdGetLabel,
+            .GetFsType = RdGetFsType,
             .ReadDirAt = RdReadDirAt,
             .Stat      = RdStat,
             .SetTimes  = nullptr,