Deduplicate data when encoding nested Cadence composites to reduce memory and storage

[fxamacker]

Updates #292 onflow/flow-go#1744 onflow/cadence#1854

When encoding nested Cadence composites, it is possible for redundant data to get encoded. For example, the same Cadence composite type and its field names can get encoded more than once when the same composite is included within the slab (aka payload, register, segment) more than once.

Suggested Solution

Deduplicate data (such as field names and types) within same segment when encoding nested composites.

Include data deduplication in PR #342 since the redesign of Atree to support inlining segments in PR #342 and #345 already requires changing the encoding format.

Combining this work with Atree Inlining avoids creating redundant work and saves time by implementing it within PR #342.

What is Outside Scope

This data deduplication is limited to the scope of a slab. It is intentionally not global deduplication. See onflow/cadence#1854 for other aspects.

[fxamacker]

Closed by #342 #345