Add missing feature designators.

[skynavga]

Add missing feature designation #unicodeBidi-version-2.

[nigelmegitt]

@skynavga Why is this needed given that we already have #unicodeBidi-isolate that deals with the values not already handled by #unicodeBidi?

[skynavga]

@nigelmegitt for consistency, since we are defining *-version-2 designations when we have extensions to existing features; more specifically, #unicodeBidi does not include #unicodeBidi-isolate, so we need a new (includes everything old + new) designation as we've done elsewhere, e.g., #animation-version-2, #bidi-version-2, etc.

[nigelmegitt]

@skynavga OK, that makes sense. From an implementation perspective it there any reason why someone might support #unicodeBidi-isolate but not #unicodeBidi?

[skynavga]

@nigelmegitt no, but the former does not logically require the latter, and vice versa