Export StringAtreeValue from the interpreter

[dsainati1]

In order to write a migration for storage to the new ordered map format, this type needs to be accessible outside of the interpreter package.

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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

[codecov-commenter]

Codecov Report

Merging #1366 (56788ef) into master (92295d5) will increase coverage by 0.00%.
The diff coverage is 92.85%.

@@           Coverage Diff           @@
##           master    #1366   +/-   ##
=======================================
  Coverage   75.83%   75.83%           
=======================================
  Files         279      279           
  Lines       38770    38770           
=======================================
+ Hits        29400    29401    +1     
+ Misses       8010     8009    -1     
  Partials     1360     1360           

Flag	Coverage Δ
unittests	75.83% <92.85%> (+<0.01%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
runtime/interpreter/encode.go	65.70% <ø> (ø)
runtime/interpreter/value.go	71.37% <90.47%> (ø)
runtime/interpreter/storagemap.go	74.48% <92.85%> (ø)
runtime/interpreter/decode.go	44.70% <100.00%> (ø)
runtime/interpreter/interpreter.go	88.14% <100.00%> (ø)
runtime/interpreter/stringatreevalue.go	81.81% <100.00%> (ø)
runtime/sema/simple_type.go	96.42% <0.00%> (+3.57%)	⬆️

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[github-actions]

Cadence Benchstat comparison

This branch with compared with the base branch onflow:master commit 92295d5
The command for i in {1..N}; do go test ./... -run=XXX -bench=. -shuffle=on; done was used.
Bench tests were run a total of 7 times on each branch.

Results

	old.txt	new.txt
	time/op		delta
QualifiedIdentifierCreation/Three_levels-2	190ns ± 1%	196ns ± 2%	+2.87%	(p=0.002 n=6+6)
RuntimeResourceDictionaryValues-2	18.6ms ± 2%	18.9ms ± 6%	~	(p=0.259 n=7+7)
RuntimeFungibleTokenTransfer-2	1.56ms ±36%	1.70ms ±19%	~	(p=0.456 n=7+7)
ParseFungibleToken-2	252µs ± 2%	252µs ± 4%	~	(p=0.945 n=6+7)
ParseDeploy/byte_array-2	26.3ms ± 4%	26.6ms ± 3%	~	(p=0.366 n=7+6)
ParseDeploy/decode_hex-2	1.57ms ± 2%	1.59ms ± 4%	~	(p=0.628 n=6+7)
ParseInfix-2	12.8µs ± 1%	13.2µs ± 9%	~	(p=0.876 n=5+7)
ParseArray-2	16.8ms ± 4%	17.1ms ± 7%	~	(p=0.445 n=6+7)
QualifiedIdentifierCreation/One_level-2	3.64ns ± 2%	3.69ns ± 2%	~	(p=0.079 n=7+7)
CheckContractInterfaceFungibleTokenConformance-2	193µs ± 6%	191µs ± 1%	~	(p=0.530 n=7+5)
ContractInterfaceFungibleToken-2	54.4µs ± 2%	53.9µs ± 3%	~	(p=0.383 n=7+7)
NewInterpreter/new_interpreter-2	1.44µs ± 9%	1.40µs ± 1%	~	(p=0.167 n=7+6)
NewInterpreter/new_sub-interpreter-2	2.73µs ± 2%	2.77µs ± 5%	~	(p=0.836 n=6+7)
InterpretRecursionFib-2	3.05ms ± 1%	3.06ms ± 2%	~	(p=0.836 n=6+7)
	alloc/op		delta
RuntimeResourceDictionaryValues-2	4.05MB ± 0%	4.05MB ± 0%	~	(p=0.383 n=7+7)
RuntimeFungibleTokenTransfer-2	277kB ± 0%	277kB ± 0%	~	(p=0.515 n=7+7)
QualifiedIdentifierCreation/One_level-2	0.00B	0.00B	~	(all equal)
QualifiedIdentifierCreation/Three_levels-2	64.0B ± 0%	64.0B ± 0%	~	(all equal)
CheckContractInterfaceFungibleTokenConformance-2	65.7kB ± 0%	65.7kB ± 0%	~	(p=0.462 n=7+7)
ContractInterfaceFungibleToken-2	26.5kB ± 0%	26.5kB ± 0%	~	(p=0.462 n=7+7)
NewInterpreter/new_interpreter-2	768B ± 0%	768B ± 0%	~	(all equal)
NewInterpreter/new_sub-interpreter-2	1.24kB ± 0%	1.24kB ± 0%	~	(all equal)
InterpretRecursionFib-2	1.24MB ± 0%	1.24MB ± 0%	~	(p=1.000 n=7+7)
	allocs/op		delta
RuntimeResourceDictionaryValues-2	102k ± 0%	102k ± 0%	~	(p=0.276 n=7+7)
RuntimeFungibleTokenTransfer-2	4.61k ± 0%	4.61k ± 0%	~	(p=0.627 n=7+7)
QualifiedIdentifierCreation/One_level-2	0.00	0.00	~	(all equal)
QualifiedIdentifierCreation/Three_levels-2	2.00 ± 0%	2.00 ± 0%	~	(all equal)
CheckContractInterfaceFungibleTokenConformance-2	1.07k ± 0%	1.07k ± 0%	~	(all equal)
ContractInterfaceFungibleToken-2	457 ± 0%	457 ± 0%	~	(all equal)
NewInterpreter/new_interpreter-2	12.0 ± 0%	12.0 ± 0%	~	(all equal)
NewInterpreter/new_sub-interpreter-2	38.0 ± 0%	38.0 ± 0%	~	(all equal)
InterpretRecursionFib-2	25.0k ± 0%	25.0k ± 0%	~	(all equal)