Lazily compute fields of account type values

[turbolent]

Description

Identified by @SupunS: Accessing accounts is a common operation and currently causes many allocations.

Reduce allocations by optimizing the value construction for the Account and its nested types: Simplify existing caching of the field/function computation, and implement it consistently for all types.

Allocations for BenchmarkRuntimeFungibleTokenTransfer:

Before: 164481 B/op	    3229 allocs/op
After:  163011 B/op	    3186 allocs/op

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• Targeted PR against master branch
• Linked to Github issue with discussion and accepted design OR link to spec that describes this work
• Code follows the standards mentioned here
• Updated relevant documentation
• Re-reviewed Files changed in the Github PR explorer
• Added appropriate labels

[github-actions]

Cadence Benchstat comparison

This branch with compared with the base branch onflow:master commit 0963441
The command for i in {1..N}; do go test ./... -run=XXX -bench=. -benchmem -shuffle=on; done was used.
Bench tests were run a total of 7 times on each branch.

Collapsed results for better readability

[SupunS]

Nice 👌