Rename project board -> column to make the UI less confusing (#30170)

This PR split the `Board` into two parts. One is the struct has been
renamed to `Column` and the second we have a `Template Type`.

But to make it easier to review, this PR will not change the database
schemas, they are just renames. The database schema changes could be in
future PRs.

---------

Co-authored-by: silverwind <me@silverwind.io>
Co-authored-by: yp05327 <576951401@qq.com>
(cherry picked from commit 98751108b11dc748cc99230ca0fc1acfdf2c8929)

Conflicts:
	docs/content/administration/config-cheat-sheet.en-us.md
	docs/content/index.en-us.md
	docs/content/installation/comparison.en-us.md
	docs/content/usage/permissions.en-us.md
	non existent files

	options/locale/locale_en-US.ini
	routers/web/web.go
	templates/repo/header.tmpl
	templates/repo/settings/options.tmpl
	trivial context conflicts

models/project/column_test.go

@@ -0,0 +1,127 @@
+// Copyright 2020 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package project
+
+import (
+	"fmt"
+	"strings"
+	"testing"
+
+	"code.gitea.io/gitea/models/db"
+	"code.gitea.io/gitea/models/unittest"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestGetDefaultColumn(t *testing.T) {
+	assert.NoError(t, unittest.PrepareTestDatabase())
+
+	projectWithoutDefault, err := GetProjectByID(db.DefaultContext, 5)
+	assert.NoError(t, err)
+
+	// check if default column was added
+	column, err := projectWithoutDefault.GetDefaultColumn(db.DefaultContext)
+	assert.NoError(t, err)
+	assert.Equal(t, int64(5), column.ProjectID)
+	assert.Equal(t, "Uncategorized", column.Title)
+
+	projectWithMultipleDefaults, err := GetProjectByID(db.DefaultContext, 6)
+	assert.NoError(t, err)
+
+	// check if multiple defaults were removed
+	column, err = projectWithMultipleDefaults.GetDefaultColumn(db.DefaultContext)
+	assert.NoError(t, err)
+	assert.Equal(t, int64(6), column.ProjectID)
+	assert.Equal(t, int64(9), column.ID)
+
+	// set 8 as default column
+	assert.NoError(t, SetDefaultColumn(db.DefaultContext, column.ProjectID, 8))
+
+	// then 9 will become a non-default column
+	column, err = GetColumn(db.DefaultContext, 9)
+	assert.NoError(t, err)
+	assert.Equal(t, int64(6), column.ProjectID)
+	assert.False(t, column.Default)
+}
+
+func Test_moveIssuesToAnotherColumn(t *testing.T) {
+	assert.NoError(t, unittest.PrepareTestDatabase())
+
+	column1 := unittest.AssertExistsAndLoadBean(t, &Column{ID: 1, ProjectID: 1})
+
+	issues, err := column1.GetIssues(db.DefaultContext)
+	assert.NoError(t, err)
+	assert.Len(t, issues, 1)
+	assert.EqualValues(t, 1, issues[0].ID)
+
+	column2 := unittest.AssertExistsAndLoadBean(t, &Column{ID: 2, ProjectID: 1})
+	issues, err = column2.GetIssues(db.DefaultContext)
+	assert.NoError(t, err)
+	assert.Len(t, issues, 1)
+	assert.EqualValues(t, 3, issues[0].ID)
+
+	err = column1.moveIssuesToAnotherColumn(db.DefaultContext, column2)
+	assert.NoError(t, err)
+
+	issues, err = column1.GetIssues(db.DefaultContext)
+	assert.NoError(t, err)
+	assert.Len(t, issues, 0)
+
+	issues, err = column2.GetIssues(db.DefaultContext)
+	assert.NoError(t, err)
+	assert.Len(t, issues, 2)
+	assert.EqualValues(t, 3, issues[0].ID)
+	assert.EqualValues(t, 0, issues[0].Sorting)
+	assert.EqualValues(t, 1, issues[1].ID)
+	assert.EqualValues(t, 1, issues[1].Sorting)
+}
+
+func Test_MoveColumnsOnProject(t *testing.T) {
+	assert.NoError(t, unittest.PrepareTestDatabase())
+
+	project1 := unittest.AssertExistsAndLoadBean(t, &Project{ID: 1})
+	columns, err := project1.GetColumns(db.DefaultContext)
+	assert.NoError(t, err)
+	assert.Len(t, columns, 3)
+	assert.EqualValues(t, 0, columns[0].Sorting) // even if there is no default sorting, the code should also work
+	assert.EqualValues(t, 0, columns[1].Sorting)
+	assert.EqualValues(t, 0, columns[2].Sorting)
+
+	err = MoveColumnsOnProject(db.DefaultContext, project1, map[int64]int64{
+		0: columns[1].ID,
+		1: columns[2].ID,
+		2: columns[0].ID,
+	})
+	assert.NoError(t, err)
+
+	columnsAfter, err := project1.GetColumns(db.DefaultContext)
+	assert.NoError(t, err)
+	assert.Len(t, columnsAfter, 3)
+	assert.EqualValues(t, columns[1].ID, columnsAfter[0].ID)
+	assert.EqualValues(t, columns[2].ID, columnsAfter[1].ID)
+	assert.EqualValues(t, columns[0].ID, columnsAfter[2].ID)
+}
+
+func Test_NewColumn(t *testing.T) {
+	assert.NoError(t, unittest.PrepareTestDatabase())
+
+	project1 := unittest.AssertExistsAndLoadBean(t, &Project{ID: 1})
+	columns, err := project1.GetColumns(db.DefaultContext)
+	assert.NoError(t, err)
+	assert.Len(t, columns, 3)
+
+	for i := 0; i < maxProjectColumns-3; i++ {
+		err := NewColumn(db.DefaultContext, &Column{
+			Title:     fmt.Sprintf("column-%d", i+4),
+			ProjectID: project1.ID,
+		})
+		assert.NoError(t, err)
+	}
+	err = NewColumn(db.DefaultContext, &Column{
+		Title:     "column-21",
+		ProjectID: project1.ID,
+	})
+	assert.Error(t, err)
+	assert.True(t, strings.Contains(err.Error(), "maximum number of columns reached"))
+}