Add more info to DApp install error messages

[dbadol]

Current situation
When manually installing a DApp fails, the GUI simply says "The DApp installation error", without further details. However, the details can be found in the log file, but that's not a straightforward operation for most users (cf. hidden system folder, long log files with many additional messages, etc.).

Solution we propose
As a few of DApp install errors are quite basic (e.g. DApp already installed, incorrect dapp file, etc.) we could give some additional information about the error right in the GUI. At least for those most common error messages that can happen when installing DApps and that users can easily solve themselves.

Possible alternatives
An alternative could be to give in the error message a direct link to the log file (same path that is given in the Settings). It would not solve the finding of the error in the log, but it would at least help finding the log file...

Screenshots
Current:

Mock-up example: