Read p12-password from env or stdin

Other secret arguments have variants like `--remote-shared-secret-env ` and `--smartcard-pin-env ` so it would make sense to add an argument `--p12-password-env` which reads from that environment variable..

Another way to pass in the secret without writing to disk is by stdin, but that's also doesn't work. By convention passing a file named `-` reads from stdin:

```
rcodesign analyze-certificate --p12-file ../empty/developer_key <<<"$DEVELOPER_KEY_PWD"
nalyze-certificate --p12-file ../empty/developer_key <<<"$DEVELOPER_KEY_PWD"
Please enter password for p12 file:
```
```
rcodesign analyze-certificate --p12-file ../empty/developer_key --p12-password-file - <<<"$DEVELOPER_KEY_PWD"
DEVELOPER_KEY_PWD" --p12-file ../empty/developer_key --p12-password-file - <<<"$D
Error: I/O error: No such file or directory (os error 2)
```

This works on linux, because `/dev/stdin` is available there: `rcodesign analyze-certificate --p12-file ../empty/developer_key --p12-password-file /dev/stdin <<<"$DEVELOPER_KEY_PWD"`

Start at the rcodesign analyze-certificate command and review the existing --remote-shared-secret-env and --smartcard-pin-env handling. Check how --p12-password-file currently reads paths, including the reported '-' case. Done means supporting --p12-password-env and a documented stdin path for p12 passwords without requiring a password file on disk.

Written by the indexing model from the issue text.