File build secrets do not support long format for specifying target

[smac89]

Description

After #9386 was merged, the build secrets seem to ignore the target parameter from long form for specifying secrets

Steps to reproduce the issue:

1. create a service with build secret specify the secrets section as

secrets:
  - source: unique_build_secret_name
    target: build_secret

2. In your Dockerfile, attempt to load the secret at /run/secrets/build_secret

Describe the results you received:
The docker is unable to find the secret at the location specified

Describe the results you expected:
The secret should have been created inside the container at the expected location

Additional information you deem important (e.g. issue happens only occasionally):

Output of docker compose version:

Docker Compose version v2.6.0

Output of docker info:

Client:
 Context:    default
 Debug Mode: false
 Plugins:
  app: Docker App (Docker Inc., v0.9.1-beta3)
  buildx: Docker Buildx (Docker Inc., v0.8.2-docker)
  compose: Docker Compose (Docker Inc., v2.6.0)
  scan: Docker Scan (Docker Inc., v0.17.0)

Server:
 Containers: 0
  Running: 0
  Paused: 0
  Stopped: 0
 Images: 202
 Server Version: 20.10.17
 Storage Driver: overlay2
  Backing Filesystem: extfs
  Supports d_type: true
  Native Overlay Diff: false
  userxattr: true
 Logging Driver: json-file
 Cgroup Driver: systemd
 Cgroup Version: 2
 Plugins:
  Volume: local
  Network: bridge host ipvlan macvlan null overlay
  Log: awslogs fluentd gcplogs gelf journald json-file local logentries splunk syslog
 Swarm: inactive
 Runtimes: crun io.containerd.runc.v2 io.containerd.runtime.v1.linux runc
 Default Runtime: runc
 Init Binary: docker-init
 containerd version: 10c12954828e7c7c9b6e0ea9b0c02b01407d3ae1
 runc version: v1.1.2-0-ga916309
 init version: de40ad0
 Security Options:
  seccomp
   Profile: default
  rootless
  cgroupns
 Kernel Version: 5.15.0-41-generic
 Operating System: Ubuntu 22.04 LTS
 OSType: linux
 Architecture: x86_64
 CPUs: 16
 Total Memory: 31.07GiB
 Name: nchukwu
 ID: SEWM:BRUO:HCYI:YSRA:JMSS:FKCK:YZ25:Y2KT:MMCP:FJU2:5MP5:KVJY
 Docker Root Dir: /opt/docker
 Debug Mode: true
  File Descriptors: 25
  Goroutines: 41
  System Time: 2022-07-14T19:52:42.348390613-06:00
  EventsListeners: 0
 Registry: https://index.docker.io/v1/
 Labels:
 Experimental: false
 Insecure Registries:
  127.0.0.0/8
 Live Restore Enabled: false

WARNING: No cpu cfs quota support
WARNING: No cpu cfs period support
WARNING: No cpu shares support
WARNING: No cpuset support
WARNING: No io.weight support
WARNING: No io.weight (per device) support
WARNING: No io.max (rbps) support
WARNING: No io.max (wbps) support
WARNING: No io.max (riops) support
WARNING: No io.max (wiops) support

Additional environment details: