[Feature Request] Add `patch` to schedule command

[LarsAlmgren]

Is your feature request related to a problem? Please describe.

I noticed that when updating a scheduled workflow with the cli, if I don't provide exactly all input it will be overwritten (empty). This is fine I guess as it's how update usually behaves. I would however like to have a patch command for schedules so I don't need to provide everything again.

Describe the solution you'd like

When I do temporal schedule patch --schedule_id abc I want the command to keep the schedule exactly the same, except for the arguments I pass.

Given the following schedule

Schedule ID: abc
Input: "hello"
Schedule spec:
[
  {
    "interval": "360s",
    "phase": "0s"
  }
]

Performing the following executions on the given schedule:
Example 1
temporal schedule patch --schedule_id abc --input 'goodbye'

Schedule ID: abc
Input: "goodbye"
Schedule spec:
[
  {
    "interval": "360s",
    "phase": "0s"
  }
]

Example 2
temporal schedule patch --schedule_id abc --interval 1m would leave the input intact

Schedule ID: abc
Input: "hello"
Schedule spec:
[
  {
    "interval": "60s",
    "phase": "0s"
  }
]

Example 3
This example is using --headers which are only available on the version built from source.
temporal schedule patch --schedule_id abc --headers 'MyHeader={"Key":123}' would leave both

Schedule ID: abc
Input: "hello"
Schedule spec:
[
  {
    "interval": "360s",
    "phase": "0s"
  }
]
Headers: MyHeader={"Key": 123}

Additional context

[LarsAlmgren]

The header part of this assumes this is fixed #938