Adds support for dot-prefixed paths in git

- in `flux bootstrap` and `flux create kustomization` etc.
- E.g. for example `--path=.flux` should work now
- Previous behaviour is to strip off any leading "." and leave you with
  "./flux" in the kustomizations / folder structure generated by `flux
  bootstrap`

Signed-off-by: Simon Howe <footless@gmail.com>

internal/flags/safe_relative_path_test.go

@@ -37,6 +37,10 @@ func TestRelativePath_Set(t *testing.T) {
 		{"traversing absolute path", "/foo/../bar", "./bar", false},
 		{"traversing overflowing absolute path", "/foo/../../../bar", "./bar", false},
 		{"empty", "", "./", false},
+		{"relative empty path", "./", "./", false},
+		{"double relative empty path", "././", "./", false},
+		{"dot path", ".foo", "./.foo", false},
+		{"relative dot path", "./.foo", "./.foo", false},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {