Exec command do not use backend options

[rdelaage]

Describe the bug
I am using mTLS to connect to my backend server so I need to use the tls-client-cert with the path to my bundle file. My config looks like this:

version: 2

extras:
  chat_fail: &chat_fail
    failure:
      - /path/to/my/fail/script.sh ${AUTORESTIC_LOCATION}

global:
  forget:
    keep-hourly: 24
    keep-daily: 7
    keep-weekly: 4
    keep-monthly: 12

backends:
  remote1:
    type: sftp
    path: remote1-backup:/backup/mySuperBackup/
  remote2:
    type: rest
    path: https://backup.remote2.example.org/mySuperBackup
    options:
      all:
        tls-client-cert: /path/to/my/certs/bundle.pem
      backup:
        compression:
          - auto

locations:
  mySuperFiles:
    from:
    - /a/path
    - /an/other/path
    to:
    - remote1
    - remote2
    cron: 0 0 * * *
    forget: "yes"
    hooks:
      <<: *chat_fail

There is no problem when running check or backup, but there is a problem with the rest backup when calling exec command. I found that autorestic do not use the user defined flags in the options section of the backend on the exec command.

Expected behavior
Autorestic use options:all and maybe options:exec ?

Environment

• OS: Debian Buster
• Version: 1.7.3

Additional context
I think we just have to add args = append(args, combineBackendOptions("exec", b)...) to this function before executing the command https://github.com/cupcakearmy/autorestic/blob/master/internal/backend.go#L140