[GUI] Launch form: upload parameters

[rodichenko]

Background It would be nice to have an option to upload parameters (as JSON or YAML file(s)) to launch / configuration forms.

Configuration forms For detached configurations and pipeline configuration forms, an Upload parameters button allows single file selection; uploaded parameters will be added to the current ones.

Launch form For launch form , an Upload button works in two modes:

• The same behavior for single file selection as for configuration forms;
• If multiple files are selected, multiple payloads will be created, i.e. launch action will create multiple jobs (a separate job for each parameters file).

Other options Let's re-use ui.launch.parameters preference (#3868) to configure "Upload" parameters button visibility, i.e. let's introduce upload_parameters property:

{
   ...
   "upload_parameters": true
   ...
}

By default, this feature is turned off (i.e., upload_parameters is false).

Parameters file format

JSON

{
  "param_1": "value1",
  "param_2": {
    "type": "string",
    "value": "value2"
  },
  "param_3": {
    "type": "boolean",
    "value": true
  },
  "param_4": false
}

YAML

---
param_1: value1
param_2: true
param_3:
  type: string
  value: value2