As `discuss_public_channel_template` is sandboxed for the `webclient`
the following CSS rule is not applied anymore.
```css
.o_web_client {
direction: ltr;
}
```
This commit adds it specifically for this template to reflect the
language direction in this sandboxed environment.
closes odoo/odoo#95893
Signed-off-by: Pierre Paridans (app) <app@odoo.com>