[lldb] Add dictionary data type to formatter bytecode (#225955)

Add a dictionary data type to formatter bytecode.

This addition will help in two ways:
1. A subsequent change will use dictionaries to model "self" ("this")
2. Many formatters internal use a dictionary as an implementation
detail, and this will allow such formatters to be compiled/ported to
formatter bytecode

Assisted-by: claude
GitOrigin-RevId: 143eb3cae4f0bcf8c0aea6cbaf04a9edf89fcfd7