Fix Abs path validation on Windows (#124084)

* Windows: Consider slash-prefixed paths as absolute

filepath.IsAbs does not consider "/" or "\" as absolute paths, even
though files can be addressed as such. [1][2]

Currently, there are some unit tests that are failing on Windows due to
this reason.

[1] https://learn.microsoft.com/en-us/dotnet/standard/io/file-path-formats#traditional-dos-paths
[2] https://learn.microsoft.com/en-us/windows/win32/fileio/naming-a-file#fully-qualified-vs-relative-paths

* Add test to verify IsAbs for windows

Signed-off-by: Maksym Pavlenko <pavlenko.maksym@gmail.com>

* Fix abs path validation on windows

Signed-off-by: Maksym Pavlenko <pavlenko.maksym@gmail.com>

* Skipp path clean check for podLogDir on windows

Signed-off-by: Maksym Pavlenko <pavlenko.maksym@gmail.com>

* Implement IsPathClean to validate path

Signed-off-by: Maksym Pavlenko <pavlenko.maksym@gmail.com>

* Add warn comment for IsAbs

Signed-off-by: Maksym Pavlenko <pavlenko.maksym@gmail.com>

---------

Signed-off-by: Maksym Pavlenko <pavlenko.maksym@gmail.com>
Co-authored-by: Claudiu Belu <cbelu@cloudbasesolutions.com>

pkg/util/filesystem/util_unix.go

@@ -22,6 +22,7 @@ package filesystem
 import (
 	"fmt"
 	"os"
+	"path/filepath"
 )
 
 // IsUnixDomainSocket returns whether a given file is a AF_UNIX socket file
@@ -35,3 +36,8 @@ func IsUnixDomainSocket(filePath string) (bool, error) {
 	}
 	return true, nil
 }
+
+// IsAbs is same as filepath.IsAbs on Unix.
+func IsAbs(path string) bool {
+	return filepath.IsAbs(path)
+}