[2.6] Small RTL issues with new whiteboard

[mokazemi]

There are a few issues in the right-to-left layout. I mention them here.

• Change slide buttons icon is wrong. The functionality is correct (Like it was in 2.5 and before). But the Next slide should use < icon instead of this >

• When the multi-user function is on, number of users are shown in the wrong place. It's like this:

But it should be like this:

BBB version: 2.6.0-alpha.2

Browser: Firefox 103.0.1