template: perms parameter not applied to directories

### Nomad version
Nomad v1.5.6
BuildDate 2023-05-19T18:26:13Z
Revision 8af70885c02ab921dedbdf6bc406a1e886866f80

### Operating system and Environment details
Ubuntu 20.04.6 LTS (Focal Fossa)

### Issue
Directories created by `template` block doesn't respect the `perms` parameter

### Reproduction steps

Create `template` block with nested directories and set `perms` parameter

```
locals {
configs = [
"telegraf.conf",
"telegraf.d/mqtt-1.conf",
"telegraf.d/mqtt-2.conf",
"telegraf.d/mqtt-3.conf",
]
}

<......>

dynamic "template" {
for_each = local.configs
content {
change_mode = "signal"
change_signal = "SIGHUP"
data = file("./local/${template.value}")
destination = "local/${template.value}"
perms = "777"
}

```

#### Expected Result
Directory structure inherit the `perms` parameter

#### Actual Result
`perms` applied to files only. Permissions for `telegraf.d` is still `drwxr-xr-x`

```
# ls -la
total 16
drwxrwxrwx 3 nobody nogroup 4096 Jun 21 14:49 .
drwxr-xr-x 1 root root 4096 Jun 21 14:49 ..
-rwxrwxrwx 1 root root 3324 Jun 21 14:49 telegraf.conf
drwxr-xr-x 2 root root 4096 Jun 21 14:49 telegraf.d

root@f6279641233b:/local# ls -la telegraf.d/
drwxr-xr-x 2 root root 4096 Jun 21 14:49 .
drwxrwxrwx 3 nobody nogroup 4096 Jun 21 14:49 ..
-rwxrwxrwx 1 root root 649 Jun 21 14:49 mqtt-1.conf
-rwxrwxrwx 1 root root 590 Jun 21 14:49 mqtt-2.conf
-rwxrwxrwx 1 root root 637 Jun 21 14:49 mqtt-3.conf
```

Trace Nomad's template block handling for nested destination paths and compare how perms are applied to files versus directories. Reproduce the example on Ubuntu, add a regression test for directory permissions, and consider the issue done when generated directories receive the configured perms without changing existing file behavior.

Written by the indexing model from the issue text.