Ability to specify state locking timeout

[Antony Southworth]

Terraform provides the -lock-timeout flag to allow waiting for the lock if it's already been acquired, instead of immediately aborting the operation with status code 1.

It would be handy if this resource provided a similar lock-timeout parameter, it could simply forward the argument to the -lock-timeout flag to Terraform.

Example step usage: wait up to 30 seconds for the lock

- put: terraform
  params:
    lock-timeout: 30s

[Lyle Franklin]

Sounds reasonable, added the "help wanted" tag if you or someone else wants to contribute this feature.