updating: show the reason why the update couldn't be completed

- include nonstd::expected library for modern error-handling
- add localized strings
- refactor updating.cpp

.github/actions/spell-check/expect.txt

@@ -1327,6 +1327,7 @@ MAPTOSAMESHORTCUT
 MAPVK
 Markdig
 martinchrzan
+martinmoene
 MATCHALLOCCURENCES
 MATCHMODE
 MAXIMIZEBOX
@@ -1504,6 +1505,7 @@ nonclient
 NONCONVERT
 NONELEVATED
 NONINFRINGEMENT
+nonstd
 nonwin
 NOOWNERZORDER
 NOPARENTNOTIFY
@@ -1573,6 +1575,7 @@ Onboarding
 onebranch
 onedrive
 onedrivelogo
+onstd
 ONITEM
 OOBE
 opencode
@@ -2148,6 +2151,7 @@ subfolder
 Subheader
 subkey
 SUBLANG
+sublicensable
 subquery
 subsetted
 subsetter