Support additional metadata in Taskfile YAML schema

[timrulebosch]

We are using Taskfiles as input for an automation system (a VSCode extenstion). For that to operate we need to know additional domain specific information about the tasks in the Taskfile. Currently, the Taskfile schema prevents adding such metadata.

Suggestion is to add a metadata object to the schema for both the Taskfile (global) and individual tasks (per task). Something like this:

---
version: '3'

vars:
  foo: bar

metadata:
  annotations:
    generator:
      repo: https://github.com/go-foo/foo
      version: v1.2.3
  labels:
    internal-only: true

tasks:
  my-task:
    desc: This task is generated by foo for project fubar.
    metadata:
       annotations: 
          generator: foo
       labels:
         project: fubar
    cmds:
      - echo "generated by foo"

If there is interest we can provide a PR as the basis for implementation.

[timrulebosch]

We decided to augment our Taskfile.yml with an additional file "Metadata.yml" (out of necessity, not because we wanted to). With that we can describe the tasks in a way that integrates with the VSCode plugin.

I think that describing this metadata within the Taskfile schema would be more practical, and would also allow some level of automated documentation generation.

As an example, here is a fragment of the metadata, and the associated Taskfile:

metadata:
  models:
    fmimcl:
      name: fmimcl
      displayName: dse.fmi.mcl
      path: dse/fmimcl
      workflows:
        - generate-fmimcl
        - patch-signalgroup
  tasks:
    generate-fmimcl:
      vars:
        FMU_DIR:
          required: true
          hint: URI identifying an FMU (select from 'uses' or manually enter a path).
        OUT_DIR:
          required: true
          hint: Directory where the model should be created (sim relative).
          default: out/model
        MCL_PATH:
          required: true
          hint: Path where the FMI MCL shared library is located.
        FMU_MODELDESC:
          required: false
          hint: Path where the FMI modelDescription.xml should be created.
          default: '{{.FMU_DIR}}/modelDescription.xml'
        SIGNAL_GROUP:
          required: false
          hint: Path where the associated Signal Group should be created.
          default: '{{.OUT_DIR}}/signalgroup.yaml'

tasks:

  generate-fmimcl:
    desc: Generate an FMI MCL from an existing FMU.
    run: always
    dir: '{{.USER_WORKING_DIR}}'
    label: dse:fmi:generate-fmimcl
    vars:
      FMU_DIR: '{{.FMU_DIR | default "FMU_DIR_NOT_SPECIFIED"}}'
      OUT_DIR: '{{.OUT_DIR | default "out/model"}}'
      MCL_PATH: '{{.MCL_PATH | default "MCL_PATH_NOT_SPECIFIED"}}'
      FMU_MODELDESC: '{{.FMU_DIR}}/modelDescription.xml'
      SIGNAL_GROUP: "{{if .SIGNAL_GROUP}}'{{.SIGNAL_GROUP}}'{{else}}'{{.OUT_DIR}}/signalgroup.yaml'{{end}}"
    cmds:
      - task: gen-mcl
        vars:
          FMU_DIR: '{{.FMU_DIR}}'
          OUT_DIR: '{{.OUT_DIR}}'
          MCL_PATH: '{{.MCL_PATH}}'
      - task: gen-signalgroup
        vars:
          INPUT: '{{.FMU_MODELDESC}}'
          OUTPUT: '{{.SIGNAL_GROUP}}'
    requires:
      vars: [FMU_DIR, MCL_PATH]