Refactor the setting to make unit test easier (#22405)

Some bugs caused by less unit tests in fundamental packages. This PR
refactor `setting` package so that create a unit test will be easier
than before.

- All `LoadFromXXX` files has been splited as two functions, one is
`InitProviderFromXXX` and `LoadCommonSettings`. The first functions will
only include the code to create or new a ini file. The second function
will load common settings.
- It also renames all functions in setting from `newXXXService` to
`loadXXXSetting` or `loadXXXFrom` to make the function name less
confusing.
- Move `XORMLog` to `SQLLog` because it's a better name for that.

Maybe we should finally move these `loadXXXSetting` into the `XXXInit`
function? Any idea?

---------

Co-authored-by: 6543 <6543@obermui.de>
Co-authored-by: delvh <dev.lh@web.de>

modules/setting/time.go

@@ -0,0 +1,64 @@
+// Copyright 2023 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package setting
+
+import (
+	"time"
+
+	"code.gitea.io/gitea/modules/log"
+)
+
+var (
+	// Time settings
+	TimeFormat string
+	// UILocation is the location on the UI, so that we can display the time on UI.
+	DefaultUILocation = time.Local
+)
+
+func loadTimeFrom(rootCfg ConfigProvider) {
+	timeFormatKey := rootCfg.Section("time").Key("FORMAT").MustString("")
+	if timeFormatKey != "" {
+		TimeFormat = map[string]string{
+			"ANSIC":       time.ANSIC,
+			"UnixDate":    time.UnixDate,
+			"RubyDate":    time.RubyDate,
+			"RFC822":      time.RFC822,
+			"RFC822Z":     time.RFC822Z,
+			"RFC850":      time.RFC850,
+			"RFC1123":     time.RFC1123,
+			"RFC1123Z":    time.RFC1123Z,
+			"RFC3339":     time.RFC3339,
+			"RFC3339Nano": time.RFC3339Nano,
+			"Kitchen":     time.Kitchen,
+			"Stamp":       time.Stamp,
+			"StampMilli":  time.StampMilli,
+			"StampMicro":  time.StampMicro,
+			"StampNano":   time.StampNano,
+		}[timeFormatKey]
+		// When the TimeFormatKey does not exist in the previous map e.g.'2006-01-02 15:04:05'
+		if len(TimeFormat) == 0 {
+			TimeFormat = timeFormatKey
+			TestTimeFormat, _ := time.Parse(TimeFormat, TimeFormat)
+			if TestTimeFormat.Format(time.RFC3339) != "2006-01-02T15:04:05Z" {
+				log.Warn("Provided TimeFormat: %s does not create a fully specified date and time.", TimeFormat)
+				log.Warn("In order to display dates and times correctly please check your time format has 2006, 01, 02, 15, 04 and 05")
+			}
+			log.Trace("Custom TimeFormat: %s", TimeFormat)
+		}
+	}
+
+	zone := rootCfg.Section("time").Key("DEFAULT_UI_LOCATION").String()
+	if zone != "" {
+		var err error
+		DefaultUILocation, err = time.LoadLocation(zone)
+		if err != nil {
+			log.Fatal("Load time zone failed: %v", err)
+		} else {
+			log.Info("Default UI Location is %v", zone)
+		}
+	}
+	if DefaultUILocation == nil {
+		DefaultUILocation = time.Local
+	}
+}