mounts: use path-based tags instead of index-based tags

[TatsuyaHayashino]

Previously, mount tags were generated using index-based naming (mount0, mount1, etc.). This caused issues when mount configuration changed: the old mount remained active with its original path while the new fstab entry used the same tag for a different path. Users had to reboot twice to apply configuration changes.

This commit generates stable mount tags by hashing both the host location and guest mountPoint. This ensures:

• Tags remain consistent across VM restarts regardless of mount order
• Configuration changes take effect after a single reboot
• Same host path mounted to multiple guest paths get unique tags

Fixes #3957

[TatsuyaHayashino]

Tests result on MacOS

❯ ./_output/bin/limactl start -y
...

❯ lima sh -c 'cat /etc/fstab; mount' | grep Users
WARN[0000] treating lima version "3432a943" from "/Users/tatsuya/.lima/default/lima-version" as very latest release 
lima-1ea3a30cd79736ef   /Users/tatsuya  virtiofs        ro,nofail,comment=cloudconfig   0  0
lima-1ea3a30cd79736ef on /Users/tatsuya type virtiofs (ro,relatime)

❯ limactl stop
...

❯ limactl start --mount-only ~/git --mount-only ~/tmp
...
     
❯ lima sh -c 'cat /etc/fstab; mount' | grep Users
WARN[0000] treating lima version "3432a943" from "/Users/tatsuya/.lima/default/lima-version" as very latest release 
bash: line 1: cd: /Users/tatsuya/Development/lima: No such file or directory
mount0  /Users/tatsuya/git      virtiofs        ro,nofail,comment=cloudconfig   0       0
mount1  /Users/tatsuya/tmp      virtiofs        ro,nofail,comment=cloudconfig   0       0
mount0 on /Users/tatsuya/git type virtiofs (ro,relatime)
mount1 on /Users/tatsuya/tmp type virtiofs (ro,relatime)