Manage iOS signing configs

## Usage

`circleci signing-config <command> [flags]`

## General Commands

| Command  | Description                  |
| -------- | ---------------------------- |
| `create` | Create an iOS signing config |
| `list`   | List iOS signing configs     |

## Targeted Commands

| Command  | Description                  |
| -------- | ---------------------------- |
| `delete` | Delete an iOS signing config |

## Flags

Global flags: `-c, --config`, `--debug`, `--no-color`, `-q, --quiet` — see `circleci --help`.

## Details

Create, list, and delete iOS signing configs.

A signing config pairs an uploaded .p12 certificate with one or more
provisioning profiles under a stable name. Reference the signing config
by name from your pipeline config under the 'code_signing' block to
install it onto the macOS runner during a job.

