Revise BigNumber support

Currently section 3.16 of the JSON-B 1.0 spec states:

> ## 3.16 Big numbers
> JSON Binding implementation MUST serialize/deserialize numbers that express greater magnitude or precision than an IEEE 754 double precision number as strings.

After [receiving some user feedback](https://github.com/eclipse-ee4j/jsonb-api/issues/112), implementations decided that this is not ideal behavior and the TCK test was challenged and excluded here: https://github.com/eclipse-ee4j/jsonb-api/issues/180

Yasson has removed this behavior here: https://github.com/eclipse-ee4j/yasson/issues/269

My current stance is that we should simply remove section 3.16 from the spec, but at minimum this section should change in some way.

Start with section 3.16 of the JSON-B 1.0 specification and review the linked discussions in issues 112 and 180, along with Yasson issue 269. Determine whether the section should be removed or revised to reflect the challenged TCK behavior and Yasson's change. Done means the specification direction is decided and the affected section is updated consistently.

Written by the indexing model from the issue text.