Consolidate reflex_base.plugins.compiler.BaseContext and reflex_base.context.base.BaseContext

**Describe the Enhancement you want** There are two very similar definitions of BaseContext which need to be consolidated, preferring the `reflex_base.context.base.BaseContext` version. While doing this, ensure that BaseContext is configured for identity equality so that two instances are only equal if they are the same instance. - What is the benefit of the enhancement? Reduce redundancy, improve semantics.