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>

routers/web/repo/projects_test.go

@@ -12,16 +12,16 @@ import (
 	"github.com/stretchr/testify/assert"
 )
 
-func TestCheckProjectBoardChangePermissions(t *testing.T) {
+func TestCheckProjectColumnChangePermissions(t *testing.T) {
 	unittest.PrepareTestEnv(t)
 	ctx, _ := contexttest.MockContext(t, "user2/repo1/projects/1/2")
 	contexttest.LoadUser(t, ctx, 2)
 	contexttest.LoadRepo(t, ctx, 1)
 	ctx.SetParams(":id", "1")
-	ctx.SetParams(":boardID", "2")
+	ctx.SetParams(":columnID", "2")
 
-	project, board := checkProjectBoardChangePermissions(ctx)
+	project, column := checkProjectColumnChangePermissions(ctx)
 	assert.NotNil(t, project)
-	assert.NotNil(t, board)
+	assert.NotNil(t, column)
 	assert.False(t, ctx.Written())
 }