feat: add a new questions API (#2813)

This PR introduces a new questions API. It is build on a single resource
`/questions` which lists all the registered questions.

```json
[
  {
    "id": 1,
    "text": "LUKS password",
    "class": "storage.luks",
    "field": {
      "type": "string"
    },
    "actions": [
      {
        "id": "accept",
        "label": "Accept"
      },
      {
        "id": "skip",
        "label": "Skip"
      }
    ],
    "defaultAction": "skip"
  }
]
```

## The new model

According to this new API, each question is composed by:

* `text`: the text for the question.
* `class`: it works as a hint for the UI or to match pre-defined answers
(e.g., "autoyast.unsupported").
* `field`: optionally, a question might define an additional field
(e.g., a password, a selector, etc.).
* `actions`: list of available actions (e.g., "next", "skip", etc.).
* `defaultAction`: default action.

## Registering a question

A new question is registered through a `POST` request to the
`/questions` API. The payload
describes the question.

```json
{
  "text": "LUKS password",
  "class": "storage.luks",
  "field": {
    "type": "string"
  },
  "actions": [
    {
      "id": "accept",
      "label": "Accept"
    },
    {
      "id": "skip",
      "label": "Skip"
    }
  ],
  "defaultAction": "skip"
}
```

## Answering a question

A question is answered by sending a `PATCH` on the connection with the
following payload.

```json
{
    "id": 1,
    "action": "accept",
    "value": "my-password"
}
```

## Automatic answers

As in the previous API, it is possible to set up the questions service
to automatically response some questions.

```json
{
  "update": {
    "questions": {
      "policy": "auto",
      "answers": [
        {
          "class": "storage.luks",
          "action": "ok",
          "value": "secret"
        }
      ]
    }
  }
}
```

## Field types

The field types allow to grow this API to cover more use cases in the
future, like software conflicts.

At this time, it supports:

* `none`: when no additional data is needed (most of the cases).
* `string`: currently unused.
* `password`: for LUKS.
* `selection`: unused but planed for software conflicts (although it
might need some improvements).

---------

Co-authored-by: Ladislav Slezák <[email protected]>

Author: imobachgs

doc/dbus/bus/org.opensuse.Agama1.Questions.Generic.bus.xml

@@ -1,18 +1,18 @@
 #!/bin/bash
 abusctl() {
-    busctl --address=unix:path=/run/agama/bus "$@"
+  busctl --address=unix:path=/run/agama/bus "$@"
 }
 
 # a stdio filter for XML introspection,
 # to fix some less clever choices made by zbus:
 # - remove detailed introspection of _child_ nodes
 # - make interfaces order deterministic by sorting them
 cleanup() {
-    # also remove the DTD declaration
-    # otherwise xmlstarlet will complain about it not being available
-    sed -e '/^<!DOCTYPE/d' -e '/http.*introspect.dtd/d' \
-        | xmlstarlet tr cleanup-zbus.xslt \
-        | xmllint  --nonet --format -
+  # also remove the DTD declaration
+  # otherwise xmlstarlet will complain about it not being available
+  sed -e '/^<!DOCTYPE/d' -e '/http.*introspect.dtd/d' |
+    xmlstarlet tr cleanup-zbus.xslt |
+    xmllint --nonet --format -
 }
 
 # "dot dot name"
@@ -21,47 +21,19 @@ DD=org.opensuse.Agama
 SS=/${DD//./\/}
 
 look() {
-    abusctl tree --list $DD.${1%.*}
-    abusctl introspect --xml-interface $DD.${1%.*} $SS/${1//./\/} \
-            | cleanup \
-            > $DD.$1.bus.xml
+  abusctl tree --list $DD.${1%.*}
+  abusctl introspect --xml-interface $DD.${1%.*} $SS/${1//./\/} |
+    cleanup \
+      >$DD.$1.bus.xml
 }
 
 look Manager1
 look Software1
 look Software1.Proposal
 look Storage1
 
-abusctl introspect --xml-interface \
-  ${DD}1 \
-  ${SS}1/Questions \
-  | cleanup \
-  > ${DD}1.Questions.bus.xml
-
-abusctl call \
-  ${DD}1 \
-  ${SS}1/Questions \
-  ${DD}1.Questions \
-  New "ssassa{ss}" "org.bands.Clash" "should I stay or should I go" 2 yes no yes 0
-abusctl introspect --xml-interface \
-  ${DD}1 \
-  ${SS}1/Questions/0 |
-  cleanup \
-    >${DD}1.Questions.Generic.bus.xml
-
-abusctl call \
-  ${DD}1 \
-  ${SS}1/Questions \
-  ${DD}1.Questions \
-  NewWithPassword "ssassa{ss}" "world.MiddleEarth.Moria.gate1" "Speak friend and enter" 2 enter giveup giveup 0
-abusctl introspect --xml-interface \
-  ${DD}1 \
-  ${SS}1/Questions/1 |
-  cleanup \
-    >${DD}1.Questions.WithPassword.bus.xml
-
 abusctl introspect --xml-interface \
   ${DD}.Manager1 \
-  ${SS}/Users1 \
-  | cleanup \
-  >${DD}.Users1.bus.xml
+  ${SS}/Users1 |
+  cleanup \
+    >${DD}.Users1.bus.xml