refactor: rename package errors to zerrors (#7039)

* chore: rename package errors to zerrors

* rename package errors to gerrors

* fix error related linting issues

* fix zitadel error assertion

* fix gosimple linting issues

* fix deprecated linting issues

* resolve gci linting issues

* fix import structure

---------

Co-authored-by: Elio Bischof <elio@zitadel.com>

internal/zerrors/unavailable_test.go

@@ -0,0 +1,33 @@
+package zerrors_test
+
+import (
+	"errors"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+
+	"github.com/zitadel/zitadel/internal/zerrors"
+)
+
+func TestUnavailableError(t *testing.T) {
+	var err interface{} = new(zerrors.UnavailableError)
+	_, ok := err.(zerrors.Unavailable)
+	assert.True(t, ok)
+}
+
+func TestThrowUnavailablef(t *testing.T) {
+	err := zerrors.ThrowUnavailablef(nil, "id", "msg")
+	//nolint:errorlint
+	_, ok := err.(*zerrors.UnavailableError)
+	assert.True(t, ok)
+}
+
+func TestIsUnavailable(t *testing.T) {
+	err := zerrors.ThrowUnavailable(nil, "id", "msg")
+	ok := zerrors.IsUnavailable(err)
+	assert.True(t, ok)
+
+	err = errors.New("I am found!")
+	ok = zerrors.IsUnavailable(err)
+	assert.False(t, ok)
+}