[WIP]Introduce explicit portable edition

[sledgehammer999]

This is an alternative to #9349.
I am not explicitly against #9349. I am just offering an alternative here. It is up to discussion.
Merits for this approach:

1. User can explicitly choose a portable edition which launches automatically in portable mode
2. Both portable and non-portable editions can switch mode by passing the correct command line parameter to the app. Users can create a wrapper script that does it.
3. Since I am going to have a portable option in the downloads page anyway, it doesn't matter to me if I compile it again for the portable version.
4. Less complicated code than Read command line parameters from <exeName>.params file #9349.

Caveat

1. This isn't meant for code review. It is a quick implementation to show an alternative. If approved, I'll welcome code reviews
2. I didn't make the necessary changes to the build systems. Those are easy and the purpose of this PR, for the moment, is as a proof-of-concept.

[sledgehammer999]

Admittedly this was quick and hacky. It would be better if I converted PORTABLE_OPTION from BoolOption to TriStateBoolOption and change the default value based on which mode we were building for.
I already did it.

[Chocobo1]

Personally I really would like not having another exe, it makes choice/maintenance complicated, such as: I must download the portable version for my usb drive and normal version for my PC at home.
Why not go with the file detection method and put out a guide that teaches users to copy/extract the exe & create a special file and done. IMHO this way is easy & widely used in Windows apps.

Since I am going to have a portable option in the downloads page anyway, it doesn't matter to me if I compile it again for the portable version.

In the way of file detection method (i.e. no separate exe way), I don't think it is insurmountable to add an option to nsis installer and create that special file.

[sledgehammer999]

In the way of file detection method (i.e. no separate exe way), I don't think it is insurmountable to add an option to nsis installer and create that special file.

I have seen both methods used. Some have the installer, some have a separate zip to download with a portable edition inside.

[glassez]

I usually don't use portable apps. But some of the applications that I use in the classic way have portable versions, and they are all distributed separately.

[glassez]

My point is this: why pay a constant runtime workload increase (each app startup) for the one-time convenience (questionable for me) when getting a portable version of the application?

[Chocobo1]

But some of the applications that I use in the classic way have portable versions, and they are all distributed separately.

I should also refine my point, for example: https://filezilla-project.org/download.php?show_all=1
FileZilla_3.37.1_win64-setup.exe
FileZilla_3.37.1_win64.zip
filezilla.exe in these 2 are really the same binary, just different packaging.

[glassez]

My point is this: why pay a constant runtime workload increase (each app startup) for the one-time convenience (questionable for me) when getting a portable version of the application?

Really I have no blocking objections to "file detecting method" if it turns out to be really more convenient for most users. @zeule's solution can be useful in some other scenarios, but it should be fixed first (currently it has known bug with params encoding on Windows).

[sledgehammer999]

OK, since there's no clear preference it's only fair to prefer #9349 due to chronological order.
As I said I have no strong feelings about any of the 2 PRs.
This will remain open until the other PR is merged/closed or in case @zeule withdraws or abandons it.

[glassez]

I think we should close it now. @sledgehammer999, @Chocobo1?