Flatpak standards update - app naming

[technosf]

Linting returns the following errors/warnings:

{
    "errors": [
        "appid-uses-code-hosting-domain"
    ],
    "info": [
        "appid-uses-code-hosting-domain: github.com"
    ],
    "message": "Please consult the documentation at https://docs.flathub.org/docs/for-app-authors/linter"
}

Tuner's flatpak app-id is com.github.louis77.tuner and current guidelines specify:

Applications using code hosting IDs and hosted on github.com, gitlab.com, codeberg.org, framagit.org must use io.github, io.gitlab, page.codeberg, io.frama prefixes depending on where the project is hosted and must have at least 4 components.

Tuners app-id should move to io.github.louis77.tuner

Also flathub App Listing Quality has a few minor issues regarding look/content

[technosf]

@louis77 Please give some thought about prioritizing and ramifications.