fix(cmd): prevent adding connection with invalid identities file

[axel7083]

Fixes #26016

Does this PR introduce a user-facing change?

Ensure identities file exists when adding ssh connection

[openshift-ci]

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[mheon]

Code LGTM

[ashley-cui]

LGTM

[Luap99]

Why print a warning? Your commit says prevent adding but this doesn't prevent it at all.
IMO simply returning the error is the easiest and there is no need for us to special case each error, the orginal error should have enough information.

[axel7083]

unthoughtful copy paste from the line bellow :p

podman/cmd/podman/system/connection/add.go

Lines 162 to 169 in ae1f0b4

	info, err := os.Stat(uri.Path)
	switch {
	case errors.Is(err, os.ErrNotExist):
	logrus.Warnf("%q does not exist", uri.Path)
	case errors.Is(err, os.ErrPermission):
	logrus.Warnf("You do not have permission to read %q", uri.Path)
	case err != nil:
	return err

anyway I applied your suggestion

[baude]

please add a test

[TomSweeneyRedHat]

LGTM
except the very unhappy tests at the moment. Time to take the draft label off?

[github-actions]

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