[71_36] focus tag first letter doesn't need to be upper case

## What
On the focus toolbar, both `bmatrix` and `Bmatrix` is displayed as
`Bmatrix`.

This pull request fix the bug.

It was ported from branch-1.1, the original author is @Yufeng-shen 

## Why
Fix ambiguity.

## How to test your changes?
```
xmake r generic-test
```

---------

Co-authored-by: Yufeng Shen <fyshen13@gmail.com>

TeXmacs/progs/generic/generic-menu.scm

@@ -35,7 +35,7 @@
           (focus-tag-name (string->symbol ns)))
         (if (symbol-unnumbered? l)
             (focus-tag-name (symbol-drop-right l 1))
-            (with r (upcase-first (tree-name (tree l)))
+            (with r (tree-name (tree l))
               (string-replace r "-" " "))))))
 
 (tm-menu (focus-variant-menu t)

TeXmacs/progs/generic/generic-test.scm

@@ -0,0 +1,32 @@
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;;
+;; MODULE      : generic-test.scm
+;; DESCRIPTION : Test suite for generic
+;; COPYRIGHT   : (C) 2022  Yufeng Shen
+;;
+;; This software falls under the GNU general public license version 3 or later.
+;; It comes WITHOUT ANY WARRANTY WHATSOEVER. For details, see the file LICENSE
+;; in the root directory or <http://www.gnu.org/licenses/gpl-3.0.html>.
+;;
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+
+(texmacs-module (generic generic-test)
+  (:use (generic generic-menu) ))
+
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;; generic menu functions
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+
+(define (regtest-focus-tag-name)
+  (regression-test-group
+   "focus-tag-name" "string"
+   focus-tag-name :none
+   (test "bmatrix" 'bmatrix "bmatrix")
+   (test "Bmatrix" 'Bmatrix "Bmatrix")
+  ))
+
+(tm-define (regtest-generic)
+  (let ((n (+ (regtest-focus-tag-name)
+              )))
+    (display* "Total: " (object->string n) " tests.\n")
+    (display "Test suite of generic: ok\n")))