Consolidate import styles

Prefer more greppable variant with 3 groups: stdlib then external deps
(which we don't have), then internal deps

app/builtin/builtin.go

@@ -4,6 +4,7 @@ import "fmt"
 import "os"
 import "os/exec"
 import "strings"
+
 import "github.com/codecrafters-io/shell-starter-go/app/core"
 
 type Builtin interface {

app/main.go

@@ -1,13 +1,11 @@
 package main
 
-import (
-	"bufio"
-	"fmt"
-	"os"
-)
+import "bufio"
+import "fmt"
+import "os"
 
-import "github.com/codecrafters-io/shell-starter-go/app/runnable"
 import "github.com/codecrafters-io/shell-starter-go/app/core"
+import "github.com/codecrafters-io/shell-starter-go/app/runnable"
 
 func getInput(ctx *core.Context) (string, error) {
 	fmt.Print("$ ")

app/runnable/runnable.go

@@ -1,11 +1,11 @@
 package runnable
 
-import "os/exec"
 import "fmt"
+import "os/exec"
 
+import "github.com/codecrafters-io/shell-starter-go/app/builtin"
 import "github.com/codecrafters-io/shell-starter-go/app/core"
 import "github.com/codecrafters-io/shell-starter-go/app/tokenize"
-import "github.com/codecrafters-io/shell-starter-go/app/builtin"
 
 type Runnable interface {
 	Run(ctx *core.Context) core.ActionResult

app/tokenize/tokenize.go

@@ -1,9 +1,7 @@
 package tokenize
 
-import (
-	"fmt"
-	"strings"
-)
+import "fmt"
+import "strings"
 
 type reader struct {
 	data string