dashboard: CPU, memory, diskIO and traffic on the footer (#15950)

* dashboard: footer, deep state update

* dashboard: resolve asset path

* dashboard: prevent state update on every reconnection

* dashboard: fix linter issue

* dashboard, cmd: minor UI fix, include commit hash

* dashboard: gitCommit renamed to commit

* dashboard: move the geth version to the right, make commit optional

* dashboard: memory, traffic and CPU on footer

* dashboard: fix merge

* dashboard: CPU, diskIO on footer

* dashboard: rename variables, use group declaration

* dashboard: docs

vendor/github.com/elastic/gosigar/sys/windows/version.go

@@ -0,0 +1,43 @@
+// +build windows
+
+package windows
+
+import (
+	"fmt"
+	"syscall"
+)
+
+// Version identifies a Windows version by major, minor, and build number.
+type Version struct {
+	Major int
+	Minor int
+	Build int
+}
+
+// GetWindowsVersion returns the Windows version information. Applications not
+// manifested for Windows 8.1 or Windows 10 will return the Windows 8 OS version
+// value (6.2).
+//
+// For a table of version numbers see:
+// https://msdn.microsoft.com/en-us/library/windows/desktop/ms724833(v=vs.85).aspx
+func GetWindowsVersion() Version {
+	// https://msdn.microsoft.com/en-us/library/windows/desktop/ms724439(v=vs.85).aspx
+	ver, err := syscall.GetVersion()
+	if err != nil {
+		// GetVersion should never return an error.
+		panic(fmt.Errorf("GetVersion failed: %v", err))
+	}
+
+	return Version{
+		Major: int(ver & 0xFF),
+		Minor: int(ver >> 8 & 0xFF),
+		Build: int(ver >> 16),
+	}
+}
+
+// IsWindowsVistaOrGreater returns true if the Windows version is Vista or
+// greater.
+func (v Version) IsWindowsVistaOrGreater() bool {
+	// Vista is 6.0.
+	return v.Major >= 6 && v.Minor >= 0
+}