Improved error messaging for remove

[decleaver]

Environment

uds v0.9.0

Steps to reproduce

1. Run uds remove on an invalid bundle

Expected result

Error messaging indicating that you're attempting to run remove with an invalid bundle name/path

Actual Result

panic: runtime error: slice bounds out of range [:6] with length 4

goroutine 1 [running]:
github.com/defenseunicorns/uds-cli/src/pkg/utils.EnsureOCIPrefix(...)
        /home/runner/work/uds-cli/uds-cli/src/pkg/utils/oci.go:250
github.com/defenseunicorns/uds-cli/src/pkg/bundle.getOCIValidatedSource({0x16bbb2ea8, 0x4})
        /home/runner/work/uds-cli/uds-cli/src/pkg/bundle/remote.go:263 +0x420
github.com/defenseunicorns/uds-cli/src/pkg/bundle.CheckOCISourcePath({0x16bbb2ea8, 0x4})
        /home/runner/work/uds-cli/uds-cli/src/pkg/bundle/remote.go:330 +0x40
github.com/defenseunicorns/uds-cli/src/pkg/bundle.(*Bundle).Remove(0x140017a6000)
        /home/runner/work/uds-cli/uds-cli/src/pkg/bundle/remove.go:28 +0x38
github.com/defenseunicorns/uds-cli/src/cmd.glob..func13(0x10b9b9d40?, {0x140003f3aa0?, 0x4?, 0x10754ba68?})
        /home/runner/work/uds-cli/uds-cli/src/cmd/uds.go:129 +0x158
github.com/spf13/cobra.(*Command).execute(0x10b9b9d40, {0x140003f3a40, 0x2, 0x2})
        /home/runner/go/pkg/mod/github.com/spf13/cobra@v1.8.0/command.go:987 +0x828
github.com/spf13/cobra.(*Command).ExecuteC(0x10b9ba8c0)
        /home/runner/go/pkg/mod/github.com/spf13/cobra@v1.8.0/command.go:1115 +0x344
github.com/spf13/cobra.(*Command).Execute(...)
        /home/runner/go/pkg/mod/github.com/spf13/cobra@v1.8.0/command.go:1039
github.com/defenseunicorns/uds-cli/src/cmd.Execute()
        /home/runner/work/uds-cli/uds-cli/src/cmd/root.go:60 +0x24
main.main()
        /home/runner/work/uds-cli/uds-cli/main.go:10 +0x1c