[IMP] web: add 'odoo' fine-tuned text-color

The '$o-theme-text-colors' provides a list of fine-tuned text-color that
differ from the bg ones since used for text.
This commit adds `$o-brand-odoo` in the list.

Commit preparatory to the introduction of dark-mode.

task-2710677

Part-of: odoo/odoo#102868

addons/web/static/src/scss/primary_variables.scss

@@ -52,6 +52,7 @@ $o-theme-text-colors: (
     "info": #0180a5,
     "warning": #9a6b01,
     "danger": #d23f3a,
+    "odoo": $o-brand-odoo,
 )!default;
 
 $o-opacity-disabled: .5 !default;

addons/web/static/src/views/form/button_box/button_box.scss

@@ -68,7 +68,7 @@
 
             .o_stat_value {
                 font-weight: $font-weight-bold;
-                color: $o-brand-odoo;
+                color: map-get($o-theme-text-colors, 'odoo');
             }
 
             .o_stat_text .o_field_empty {