patch 8.2.1624: Vim9: cannot pass "true" to split(), str2nr() and strchars()

Problem:    Vim9: cannot pass "true" to split(), str2nr() and strchars().
Solution:   Use tv_get_bool_chk(). (closes #6884, closes #6885, closes #6886)
diff --git a/src/evalfunc.c b/src/evalfunc.c
index 810769a..e7683fc 100644
--- a/src/evalfunc.c
+++ b/src/evalfunc.c
@@ -7884,7 +7884,7 @@
 	if (pat == NULL)
 	    typeerr = TRUE;
 	if (argvars[2].v_type != VAR_UNKNOWN)
-	    keepempty = (int)tv_get_number_chk(&argvars[2], &typeerr);
+	    keepempty = (int)tv_get_bool_chk(&argvars[2], &typeerr);
     }
     if (pat == NULL || *pat == NUL)
 	pat = (char_u *)"[\\x01- ]\\+";
@@ -8030,7 +8030,7 @@
 	    emsg(_(e_invarg));
 	    return;
 	}
-	if (argvars[2].v_type != VAR_UNKNOWN && tv_get_number(&argvars[2]))
+	if (argvars[2].v_type != VAR_UNKNOWN && tv_get_bool(&argvars[2]))
 	    what |= STR2NR_QUOTE;
     }
 
@@ -8155,12 +8155,12 @@
 f_strchars(typval_T *argvars, typval_T *rettv)
 {
     char_u		*s = tv_get_string(&argvars[0]);
-    int			skipcc = 0;
+    int			skipcc = FALSE;
     varnumber_T		len = 0;
     int			(*func_mb_ptr2char_adv)(char_u **pp);
 
     if (argvars[1].v_type != VAR_UNKNOWN)
-	skipcc = (int)tv_get_number_chk(&argvars[1], NULL);
+	skipcc = (int)tv_get_bool(&argvars[1]);
     if (skipcc < 0 || skipcc > 1)
 	emsg(_(e_invarg));
     else