Fix and simplify parser buffering

[SupunS]

Port of https://github.com/dapperlabs/cadence-internal/pull/41 authored by Bastian.

Description

Description from original PR:

Joe had identified a bug in the parser: Buffering does not handle nesting properly: https://github.com/jsatdapr/fuzzing/pull/2

The parser gets confused when doing nested lookaheads. This means someone can write code that looks like it says one thing, but does the opposite. The failure path is complex and can probably be tricked into doing arbitrarily interesting things beyond the simple testcases given here. Even still, a script that reads like -1 but runs like +1 is enough to do interesting things already.

Instead of complicating the already complicated buffering logic in the parser even further, fix and simplify it by:

• Refactoring the lexer to run in advance and lexing all tokens
• Adding support for rewinding to an earlier token stream position
• Keeping a stack of token stream positions and buffered errors in the parser
• Properly pushing and popping the two stacks (token stream positions and buffered errors) for nested bufferings

This also also increases performance to 2x for the FT contract.

---

• 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 2eb9cf7
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
RuntimeFungibleTokenTransfer-2	1.77ms ±20%	1.77ms ±36%	~	(p=0.535 n=7+7)
RuntimeResourceDictionaryValues-2	18.6ms ± 3%	18.9ms ± 4%	~	(p=0.535 n=7+7)
QualifiedIdentifierCreation/One_level-2	3.58ns ± 3%	3.55ns ± 4%	~	(p=0.620 n=7+7)
QualifiedIdentifierCreation/Three_levels-2	181ns ± 3%	185ns ± 4%	~	(p=0.068 n=7+7)
ContractInterfaceFungibleToken-2	53.1µs ± 3%	53.3µs ± 5%	~	(p=0.699 n=6+6)
CheckContractInterfaceFungibleTokenConformance-2	189µs ± 3%	186µs ± 5%	~	(p=0.366 n=6+7)
NewInterpreter/new_interpreter-2	1.36µs ± 6%	1.34µs ± 3%	~	(p=0.334 n=7+7)
NewInterpreter/new_sub-interpreter-2	2.61µs ± 4%	2.65µs ± 5%	~	(p=0.534 n=7+6)
InterpretRecursionFib-2	3.06ms ± 3%	3.14ms ± 3%	~	(p=0.128 n=7+7)
ParseDeploy/decode_hex-2	1.63ms ± 4%	1.55ms ± 6%	−5.14%	(p=0.007 n=7+7)
ParseDeploy/byte_array-2	39.2ms ± 3%	26.3ms ± 5%	−33.09%	(p=0.001 n=7+7)
ParseArray-2	25.9ms ± 3%	17.2ms ±15%	−33.47%	(p=0.001 n=7+7)
ParseInfix-2	27.9µs ± 4%	13.0µs ±10%	−53.40%	(p=0.001 n=7+7)
ParseFungibleToken-2	537µs ± 6%	245µs ± 4%	−54.40%	(p=0.001 n=7+6)
	alloc/op		delta
RuntimeFungibleTokenTransfer-2	238kB ± 0%	273kB ± 0%	+14.60%	(p=0.001 n=7+7)
RuntimeResourceDictionaryValues-2	4.04MB ± 0%	4.05MB ± 0%	+0.42%	(p=0.001 n=7+6)
QualifiedIdentifierCreation/One_level-2	0.00B	0.00B	~	(all equal)
QualifiedIdentifierCreation/Three_levels-2	64.0B ± 0%	64.0B ± 0%	~	(all equal)
ContractInterfaceFungibleToken-2	26.5kB ± 0%	26.5kB ± 0%	~	(p=0.462 n=7+7)
CheckContractInterfaceFungibleTokenConformance-2	65.7kB ± 0%	65.7kB ± 0%	~	(p=0.070 n=7+7)
NewInterpreter/new_interpreter-2	720B ± 0%	720B ± 0%	~	(all equal)
NewInterpreter/new_sub-interpreter-2	1.18kB ± 0%	1.18kB ± 0%	~	(all equal)
InterpretRecursionFib-2	1.24MB ± 0%	1.24MB ± 0%	~	(p=0.192 n=7+7)
	allocs/op		delta
RuntimeFungibleTokenTransfer-2	4.54k ± 0%	4.54k ± 0%	~	(p=0.592 n=7+7)
RuntimeResourceDictionaryValues-2	102k ± 0%	102k ± 0%	~	(p=0.070 n=7+6)
QualifiedIdentifierCreation/One_level-2	0.00	0.00	~	(all equal)
QualifiedIdentifierCreation/Three_levels-2	2.00 ± 0%	2.00 ± 0%	~	(all equal)
ContractInterfaceFungibleToken-2	457 ± 0%	457 ± 0%	~	(all equal)
CheckContractInterfaceFungibleTokenConformance-2	1.07k ± 0%	1.07k ± 0%	~	(all equal)
NewInterpreter/new_interpreter-2	11.0 ± 0%	11.0 ± 0%	~	(all equal)
NewInterpreter/new_sub-interpreter-2	36.0 ± 0%	36.0 ± 0%	~	(all equal)
InterpretRecursionFib-2	25.0k ± 0%	25.0k ± 0%	~	(all equal)