Fix parsing of reference expressions

[turbolent]

Description

Reference expressions are parsed by parsing them as a casting expression.

Currently the reference operator & parses any expression, which leads to confusing error messages for valid programs.
For example, currently an expression &v as &T? ?? panic("no v") is parsed as a reference to a nil-coalescing operation (??), instead of a nil-coalescing operation of a reference expression.

Only parse an expression which has a precedence as high as a casting expression, the expression kind we expect to parse.

This is not a breaking change: Previously the expressions were not accepted, now they will be.

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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]

Codecov Report

Merging #1622 (f8e663e) into master (f615bea) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master    #1622   +/-   ##
=======================================
  Coverage   74.73%   74.73%           
=======================================
  Files         288      288           
  Lines       55340    55339    -1     
=======================================
+ Hits        41357    41358    +1     
+ Misses      12489    12487    -2     
  Partials     1494     1494           

Flag	Coverage Δ
unittests	74.73% <100.00%> (+<0.01%)	⬆️

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

Impacted Files	Coverage Δ
runtime/parser2/expression.go	92.80% <100.00%> (-0.01%)	⬇️
runtime/interpreter/storage.go	72.78% <0.00%> (+1.36%)	⬆️

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[github-actions]

Cadence Benchstat comparison

This branch with compared with the base branch onflow:master commit f615bea
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
RuntimeResourceDictionaryValues-2	5.90ms ± 6%	5.76ms ± 1%	~	(p=0.343 n=7+5)
RuntimeFungibleTokenTransfer-2	985µs ±32%	1170µs ±28%	~	(p=0.318 n=7+7)
Transfer-2	76.7ns ± 4%	74.8ns ± 7%	~	(p=0.209 n=7+7)
ParseDeploy/byte_array-2	17.7ms ± 3%	18.4ms ±10%	~	(p=0.165 n=7+7)
ParseDeploy/decode_hex-2	1.04ms ± 6%	1.04ms ± 7%	~	(p=0.620 n=7+7)
ParseArray-2	11.5ms ±11%	11.2ms ± 4%	~	(p=0.620 n=7+7)
ParseFungibleToken-2	166µs ± 8%	158µs ± 1%	~	(p=0.073 n=7+6)
ParseInfix-2	7.70µs ±10%	7.64µs ± 4%	~	(p=1.000 n=7+7)
QualifiedIdentifierCreation/One_level-2	2.02ns ± 1%	2.20ns ± 9%	~	(p=0.168 n=6+7)
QualifiedIdentifierCreation/Three_levels-2	125ns ± 3%	124ns ± 7%	~	(p=0.829 n=7+7)
ContractInterfaceFungibleToken-2	35.8µs ± 5%	36.0µs ±10%	~	(p=0.902 n=7+7)
CheckContractInterfaceFungibleTokenConformance-2	118µs ± 9%	116µs ± 6%	~	(p=0.620 n=7+7)
NewInterpreter/new_interpreter-2	1.03µs ± 4%	1.03µs ± 6%	~	(p=0.535 n=7+7)
NewInterpreter/new_sub-interpreter-2	2.02µs ± 8%	2.03µs ± 1%	~	(p=0.704 n=7+6)
InterpretRecursionFib-2	2.45ms ± 3%	2.43ms ± 7%	~	(p=0.620 n=7+7)
	alloc/op		delta
RuntimeResourceDictionaryValues-2	2.25MB ± 0%	2.25MB ± 0%	~	(p=0.620 n=7+7)
RuntimeFungibleTokenTransfer-2	273kB ± 0%	273kB ± 0%	~	(p=0.805 n=7+7)
Transfer-2	48.0B ± 0%	48.0B ± 0%	~	(all equal)
QualifiedIdentifierCreation/One_level-2	0.00B	0.00B	~	(all equal)
QualifiedIdentifierCreation/Three_levels-2	64.0B ± 0%	64.0B ± 0%	~	(all equal)
ContractInterfaceFungibleToken-2	26.7kB ± 0%	26.7kB ± 0%	~	(p=1.000 n=7+7)
CheckContractInterfaceFungibleTokenConformance-2	66.3kB ± 0%	66.3kB ± 0%	~	(p=0.385 n=6+7)
NewInterpreter/new_interpreter-2	848B ± 0%	848B ± 0%	~	(all equal)
NewInterpreter/new_sub-interpreter-2	1.34kB ± 0%	1.34kB ± 0%	~	(all equal)
InterpretRecursionFib-2	1.14MB ± 0%	1.14MB ± 0%	~	(p=1.000 n=7+7)
	allocs/op		delta
RuntimeResourceDictionaryValues-2	37.6k ± 0%	37.6k ± 0%	~	(p=1.000 n=5+7)
RuntimeFungibleTokenTransfer-2	4.58k ± 0%	4.58k ± 0%	~	(p=0.164 n=7+7)
Transfer-2	1.00 ± 0%	1.00 ± 0%	~	(all equal)
QualifiedIdentifierCreation/One_level-2	0.00	0.00	~	(all equal)
QualifiedIdentifierCreation/Three_levels-2	2.00 ± 0%	2.00 ± 0%	~	(all equal)
ContractInterfaceFungibleToken-2	460 ± 0%	460 ± 0%	~	(all equal)
CheckContractInterfaceFungibleTokenConformance-2	1.07k ± 0%	1.07k ± 0%	~	(all equal)
NewInterpreter/new_interpreter-2	13.0 ± 0%	13.0 ± 0%	~	(all equal)
NewInterpreter/new_sub-interpreter-2	40.0 ± 0%	40.0 ± 0%	~	(all equal)
InterpretRecursionFib-2	23.8k ± 0%	23.8k ± 0%	~	(all equal)