Make license dual license

[AligningEntropy]

Enables Bruno to support dual MIT and proprietary licensed.

[flathubbot]

Started test build 133372

[flathubbot]

Build 133372 successful
To test this build, install it from the testing repository:

flatpak install --user https://dl.flathub.org/build-repo/116374/com.usebruno.Bruno.flatpakref

[AligningEntropy]

In #1 the issue of the proprietary license was addressed by marking it as MIT which matches the official Github Repo license.

However, there appears to be an interest 1,2 in dual licensing Bruno under both MIT and a separate proprietary license. As such,this license fix was reverted in Release 1.18.0 #22 which has resulted in the proprietary badge appearing again.

This PR attempts to enable this dual licensing by utilizing the supported expression operator AND.

Ideally, according to the docs, the proprietary license will be linked to like <project_license>MIT AND LicenseRef-proprietary=https://usebruno.com/license</project_license>; however, I cannot find any mention of such a proprietary license on the Homepage, official documentation websites, or the Github Repo. As such I have left it blank which should still work as before.

This does raise the issue of, what is Bruno's license? By all accounts except this flatpaks metadata Bruno is MIT licensed; however, it appears that @helloanoop wants this to be proprietary as well. If that is the case, then this should be better publicized (in intention and actual legal license) on the official pages/repo.

This PR does not address this legal issue, rather it just tries to align with what appears to be the immediate intent.

[flathubbot]

Started test build 141339

[flathubbot]

Build 141339 successful
To test this build, install it from the testing repository:

flatpak install --user https://dl.flathub.org/build-repo/124392/com.usebruno.Bruno.flatpakref

[jwetzell]

@AligningEntropy the repo IS MIT licensed, however the "binaries" attached to the releases on that repo and distributed via things like (apt, flathub, etc.) are a combination of the MIT code in the public repo and private code. I don't now enough about licenses to know how that should be classified but hopefully that clarifies what is going on here.

[flathubbot]

Started test build 141575

[flathubbot]

Build 141575 successful
To test this build, install it from the testing repository:

flatpak install --user https://dl.flathub.org/build-repo/124632/com.usebruno.Bruno.flatpakref

[Eonfge]

This application should stay 'Proprietary', unless it is build from source. The external package has a non-free license.

This is not the first application with that problem. VS Code from Microsoft has the same non-free approach.