t7410: rename to t2405-worktree-submodule.sh

t7410: rename to t2405-worktree-submodule.sh

This test was added in df56607dff (git-common-dir: make "modules/"
per-working-directory directory, 2014-11-30), back when the 'git worktree' command
did not exist and 'git checkout --to' was used to create supplementary worktrees.

Since this file contains tests for the interaction of 'git worktree' with
submodules, rename it to t2405-worktree-submodule.sh, following the naming scheme for
tests checking the behavior of various commands with submodules.

Signed-off-by: Philippe Blain <redacted>
Signed-off-by: Junio C Hamano <redacted>