[WIP] add option for extended logging

[tessus]

I believe there is a bug in the config code.

As soon as there is a default value defined in the struct, env vars seem to be ignored.

I have added a debug output for you to see the problem:

$ export GOTIFY_EXTENDEDLOGFORMAT=false
$ ./gotify-server
init() ExtendedLogFormat = true
Starting Gotify version 2.2.4-4-g62a1c99@2023-05-23-17:37:16
Started Listening for plain HTTP connection on :80

If you remove the default default:"true" in config/config.go, it works. (It will heed the value of GOTIFY_EXTENDEDLOGFORMAT.)

I have marked this PR as work in progress, since I ran into this little problem and because you haven't decided whether you want to add this yet.

However, please let me stress this again: a TZ info is rather important. I am pretty sure that most system admins will agree. The "[GIN] " text is also not very useful.
You also mentioned using a standard format like Apache/nginx. I have to say that the default Apache or NCSA log format does not use a proper date format. Your log looks actually quite nice. The pipe symbols are perfectly valid field separators, because they are not part of any of the fields' potential values.

Fixes #565

[jmattheis]

I've changed the date time format to RFC3339.

[codecov]

Codecov Report

Patch coverage: 100.00% and no project coverage change.

Comparison is base (8f51a2c) 86.09% compared to head (9676fe9) 86.09%.

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #567   +/-   ##
=======================================
  Coverage   86.09%   86.09%           
=======================================
  Files          45       45           
  Lines        1568     1568           
=======================================
  Hits         1350     1350           
  Misses        137      137           
  Partials       81       81           

Impacted Files	Coverage Δ
router/router.go	88.00% <100.00%> (ø)

☔ View full report in Codecov by Sentry.
📢 Do you have feedback about the report comment? Let us know in this issue.

[tessus]

RFC3339 works too. ;-) I didn't use it, because I thought you might think that it is not as readable because of the T between the date and time.

Thanks for the change.