[chore] Global server configuration overhaul (#575)

* move config flag names and usage to config package, rewrite config package to use global Configuration{} struct

Signed-off-by: kim <grufwub@gmail.com>

* improved code comment

Signed-off-by: kim <grufwub@gmail.com>

* linter

Signed-off-by: kim <grufwub@gmail.com>

* fix unmarshaling

Signed-off-by: kim <grufwub@gmail.com>

* remove kim's custom go compiler changes

Signed-off-by: kim <grufwub@gmail.com>

* generate setter and flag-name functions, implement these in codebase

Signed-off-by: kim <grufwub@gmail.com>

* update deps

Signed-off-by: kim <grufwub@gmail.com>

* small change

Signed-off-by: kim <grufwub@gmail.com>

* appease the linter...

Signed-off-by: kim <grufwub@gmail.com>

* move configuration into ConfigState structure, ensure reloading to/from viper settings to keep in sync

Signed-off-by: kim <grufwub@gmail.com>

* lint

Signed-off-by: kim <grufwub@gmail.com>

* update code comments

Signed-off-by: kim <grufwub@gmail.com>

* fix merge issue

Signed-off-by: kim <grufwub@gmail.com>

* fix merge issue

Signed-off-by: kim <grufwub@gmail.com>

* improved version string (removes time + go version)

Signed-off-by: kim <grufwub@gmail.com>

* fix version string build to pass test script + consolidate logic in func

Signed-off-by: kim <grufwub@gmail.com>

* add license text, update config.Defaults comment

Signed-off-by: kim <grufwub@gmail.com>

* add license text to generated config helpers file

Signed-off-by: kim <grufwub@gmail.com>

* defer unlock on config.Set___(), to ensure unlocked on panic

Signed-off-by: kim <grufwub@gmail.com>

* make it more obvious which cmd flags are being attached

Signed-off-by: kim <grufwub@gmail.com>

internal/email/sender.go

@@ -23,7 +23,6 @@ import (
 	"net/smtp"
 	"text/template"
 
-	"github.com/spf13/viper"
 	"github.com/superseriousbusiness/gotosocial/internal/config"
 )
 
@@ -38,19 +37,17 @@ type Sender interface {
 
 // NewSender returns a new email Sender interface with the given configuration, or an error if something goes wrong.
 func NewSender() (Sender, error) {
-	keys := config.Keys
-
-	templateBaseDir := viper.GetString(keys.WebTemplateBaseDir)
+	templateBaseDir := config.GetWebTemplateBaseDir()
 	t, err := loadTemplates(templateBaseDir)
 	if err != nil {
 		return nil, err
 	}
 
-	username := viper.GetString(keys.SMTPUsername)
-	password := viper.GetString(keys.SMTPPassword)
-	host := viper.GetString(keys.SMTPHost)
-	port := viper.GetInt(keys.SMTPPort)
-	from := viper.GetString(keys.SMTPFrom)
+	username := config.GetSMTPUsername()
+	password := config.GetSMTPPassword()
+	host := config.GetSMTPHost()
+	port := config.GetSMTPPort()
+	from := config.GetSMTPFrom()
 
 	return &sender{
 		hostAddress: fmt.Sprintf("%s:%d", host, port),