[Feature Request]: Get installed QGIS versions

Context

When creating shortcuts, QDT needs to know the location of the QGIS executable to point to.

Currently, this is done by defining the QDT_QGIS_EXE_PATH environment variable, then fallbacking to searching with which or then a hard-coded value corresponding to the default path of the latest LTR official msi installer.

Description

Add a new job to find a QGIS installed version to use:

Expected logic

retrieve published versions of QGIS with dates and type (LTR, normal...) calling the Github API to list tags on qgis/qgis
integrate this in the form of a sub-command (qdt check-installed-qgis) for example, which outputs a structured file (with associated JSON schema)
- this file is embedded into the packaging during the CI (for offline use)
- this file is published in the documentation (this may be useful to others)
- if not, dynamic calls can be made from the internal code
the sub-command compares the published and installed versions:
- predefined environment variable (to allow admins to specify the version officially supported by the IS)
- registry (winreg) for Windows
- known paths: C:\OSGeo4W64, etc.
- :warning: manage access rights errors, in particular the listing on %PROGRAMFILES%: execution in non-admin mode by default
- for linux, there's less effort to be made a priori, which is sufficient in most cases

Sample job configuration:

Not contractual.

- name: Find installed QGIS
  uses: qgis-installation-finder
  with:
    versions_priority:
      - !ENV["QDT_QGIS_PREFERRED_VERSION", "ltr"]
      - 3.28
      - 3.30
    if_not_found: error

Sample structured list

Not contractual.

{
    "updated": "2023-05-29 12:35:00",
    "published_versions": [
        {
            "major": "3",
            "minor": "28",
            "potential_ltr": true,
            "supported_until": "2024-02-10 00:00:00",
            "patches": [
                {
                    "patch": "6",
                    "published": "2023-05-29 01:00:00",
                    "type": "ltr"
                },
                {
                    "patch": "5",
                    "published": "2023-04-29 01:00:00",
                    "type": "ltr"
                },
                [...]
                {
                    "patch": "0",
                    "published": "2022-10-14 01:00:00",
                    "type": "regular"
                }
            ]
        },
        {
            "major": "3",
            "minor": "30",
            "potential_ltr": false,
            "supported_until": "2023-08-10 00:00:00",
            "patches": [
                {
                    "patch": "2",
                    "published": "2023-05-29 01:00:00",
                    "type": "regular"
                }
            ]
        }
    ]
}

Use Cases

In Windows, there are often multiple versions installed. It could help to avoid requiring an environment variable to be set

Impacted jobs:

shortcuts manager
profiles sync: check if the profile is compatible with installed QGIS versions

Visuals

No response

Before submitting

[X] I have verified that my idea is a change request and not a bug report.

Guts / qgis-deployment-cli