Update generic error message in login screen

[tomasMizera]

Changed the generic error message, it is visible if the server is unavailable or the app does not have an internet connection. Previously the text did not mention the possibility of no internet connection.

[github-actions]

Pull Request Test Coverage Report for Build 9254868188

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 6 unchanged lines in 2 files lost coverage.
• Overall coverage decreased (-0.04%) to 59.936%

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Files with Coverage Reduction	New Missed Lines	%
input/core/merginapi.cpp	3	78.58%
input/core/merginuserinfo.cpp	3	73.76%

Totals
Change from base Build 9251419383:	-0.04%
Covered Lines:	7670
Relevant Lines:	12797

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💛 - Coveralls