Refactor project templates (#26448)

This PR refactors a bunch of projects-related code, mostly the
templates.
The following things were done:
  - rename boards to columns in frontend code
  - use the new `ctx.Locale.Tr` method
  - cleanup template, remove useless newlines, classes, comments
  - merge org-/user and repo level project template together
    - move "new column" button into project toolbar
- move issue card (shared by projects and pinned issues) to shared
template, remove useless duplicated styles
- add search function to projects (to make the layout more similar to
milestones list where it is inherited from 😆)
  - maybe more changes I forgot I've done 😆 

Closes #24893

After:
![Bildschirmfoto vom 2023-08-10
23-02-00](https://github.com/go-gitea/gitea/assets/47871822/cab61456-1d23-4373-8163-e567f1b3b5f9)
![Bildschirmfoto vom 2023-08-10
23-02-26](https://github.com/go-gitea/gitea/assets/47871822/94b55d60-5572-48eb-8111-538a52d8bcc6)
![Bildschirmfoto vom 2023-08-10
23-02-46](https://github.com/go-gitea/gitea/assets/47871822/a0358f4b-4e05-4194-a7bc-6e0ecba5a9b6)

---------

Co-authored-by: silverwind <me@silverwind.io>

models/project/project.go

@@ -198,6 +198,7 @@ type SearchOptions struct {
 	IsClosed util.OptionalBool
 	OrderBy  db.SearchOrderBy
 	Type     Type
+	Title    string
 }
 
 func (opts *SearchOptions) toConds() builder.Cond {
@@ -218,6 +219,10 @@ func (opts *SearchOptions) toConds() builder.Cond {
 	if opts.OwnerID > 0 {
 		cond = cond.And(builder.Eq{"owner_id": opts.OwnerID})
 	}
+
+	if len(opts.Title) != 0 {
+		cond = cond.And(db.BuildCaseInsensitiveLike("title", opts.Title))
+	}
 	return cond
 }