[GITEA] Add password length check on install page

- Resolves go-gitea#271
- Ensure that the adminstrator password is at least `MIN_PASSWORD_LENGTH`.

(cherry picked from commit 28cb04c3f5040980e716ce66cd5906f324257e02)
(cherry picked from commit 95371ebd92cd005e2d50a4754e60525cf6135b86)
(cherry picked from commit a134288ab6b0291082d913c4e22456b31af58af9)
(cherry picked from commit 4202f052cb32aec71a61dd2afd814035a9d85eea)
(cherry picked from commit 510b7467d3ee0bf346ad1843775affe1df0675ae)
(cherry picked from commit f3a6e1f121e89aaf608fd9890eaf06ed939d1006)
(cherry picked from commit f340508819866f355feec6d01b349fa7df29ace9)
(cherry picked from commit b891bb176d48c3855cc5b6e4573e7a337af9d382)
(cherry picked from commit 1a1bfc38cc7863f5cb3022560cacb2006d08f113)
(cherry picked from commit 083d5aefed10e54814c4438eabcd01973d305502)
(cherry picked from commit 4586096be9b6214058245da3227541866ea4312f)
(cherry picked from commit 039fa20cc8a5b50d5cc37de4503e8a9a80042bcc)

routers/install/install.go

@@ -358,6 +358,12 @@ func SubmitInstall(ctx *context.Context) {
 			ctx.RenderWithErr(ctx.Tr("form.password_not_match"), tplInstall, form)
 			return
 		}
+		if len(form.AdminPasswd) < setting.MinPasswordLength {
+			ctx.Data["Err_Admin"] = true
+			ctx.Data["Err_AdminPasswd"] = true
+			ctx.RenderWithErr(ctx.Tr("auth.password_too_short", setting.MinPasswordLength), tplInstall, form)
+			return
+		}
 	}
 
 	// Init the engine with migration