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>

models/project/template.go

@@ -0,0 +1,45 @@
+// Copyright 2024 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package project
+
+type (
+	// TemplateType is used to represent a project template type
+	TemplateType uint8
+
+	// TemplateConfig is used to identify the template type of project that is being created
+	TemplateConfig struct {
+		TemplateType TemplateType
+		Translation  string
+	}
+)
+
+const (
+	// TemplateTypeNone is a project template type that has no predefined columns
+	TemplateTypeNone TemplateType = iota
+
+	// TemplateTypeBasicKanban is a project template type that has basic predefined columns
+	TemplateTypeBasicKanban
+
+	// TemplateTypeBugTriage is a project template type that has predefined columns suited to hunting down bugs
+	TemplateTypeBugTriage
+)
+
+// GetTemplateConfigs retrieves the template configs of configurations project columns could have
+func GetTemplateConfigs() []TemplateConfig {
+	return []TemplateConfig{
+		{TemplateTypeNone, "repo.projects.type.none"},
+		{TemplateTypeBasicKanban, "repo.projects.type.basic_kanban"},
+		{TemplateTypeBugTriage, "repo.projects.type.bug_triage"},
+	}
+}
+
+// IsTemplateTypeValid checks if the project template type is valid
+func IsTemplateTypeValid(p TemplateType) bool {
+	switch p {
+	case TemplateTypeNone, TemplateTypeBasicKanban, TemplateTypeBugTriage:
+		return true
+	default:
+		return false
+	}
+}