Make BAT matching promotion configurable

[bsclifton]

This is a sub-task of #11100

Description

The promotion should be able to be turned on or off (client side) via a single configuration value. This config setting would be checked by other issues, such as #11867 and #11868

When disabled

Promotional text will not be shown

When enabled

We can either:

• make a call to the back end to see if the promotion is still in effect
  OR
• show the promotion

[NejcZdovc]

@bsclifton I think that all configuration will be done in libraries/server and browser will just read data. This way we don't need to deploy new version to turn promotion on/off

cc @mrose17

[mrose17]

@NejcZdovc - that is my belief as well. it is all data-driven! i hope to have the repos updated by COB us/pacific!

[bsclifton]

@NejcZdovc totally agree- as long as the bat-client can handle offline scenarios (returning false for promotion enabled, for example)

[bsclifton]

Fixed with #11874 - all info comes from server side