Various fixes and improvements (#1643)

- allow repo names to be case-insensitive
- improve backend error handling on DB get errors (record not found ->
404, else -> 500)
- replace magic numbers of http response codes
- unify the look and feel of cancel / save buttons on forms and view
them in one line

---------

Co-authored-by: Lauris BH <lauris@nix.lv>

server/api/helper.go

@@ -20,6 +20,7 @@ import (
 
 	"github.com/gin-gonic/gin"
 	"github.com/rs/zerolog/log"
+	"github.com/woodpecker-ci/woodpecker/server/store/types"
 
 	"github.com/woodpecker-ci/woodpecker/server"
 	"github.com/woodpecker-ci/woodpecker/server/forge"
@@ -40,6 +41,14 @@ func handlePipelineErr(c *gin.Context, err error) {
 	}
 }
 
+func handleDbGetError(c *gin.Context, err error) {
+	if errors.Is(err, types.RecordNotExist) {
+		c.AbortWithStatus(http.StatusNotFound)
+		return
+	}
+	_ = c.AbortWithError(http.StatusInternalServerError, err)
+}
+
 // if the forge has a refresh token, the current access token may be stale.
 // Therefore, we should refresh prior to dispatching the job.
 func refreshUserToken(c *gin.Context, user *model.User) {