[DRAFT] Refactor quant nonmutating

[milseman]

Refactor off of mutating methods

Refactors mutating methods into string methods for easier unit testing and parity-checking via assertions. Prepares for more efficient implementations.

Doing so creates many small-to-medium regressions, unfortunately, so this should only be done in conjunction with more refactorings and improvements.

[milseman]

This is built on top of #706, which has many improvements.

This refactoring, compared to just #706, has the following perf and regressions. They could be ARC-related, haven't explored exactly what's going on here:

=== Regressions ======================================================================
- CompilerMessages_All_Scalar             73.7ms	69.9ms	3.77ms		5.4%
- EmailRFCNoMatches_All_Scalar            126ms	122ms	3.74ms		3.1%
- CompilerMessages_All                    90.1ms	86.7ms	3.42ms		3.9%
- SubtractionCCC_All                      23ms	20.9ms	2.07ms		9.9%
- DiceRollsInText_All                     42.9ms	41.1ms	1.82ms		4.4%
- BasicCCC_All                            7.32ms	5.93ms	1.38ms		23.3%
- EmojiRegex_All_Scalar                   41.9ms	40.5ms	1.37ms		3.4%
- BasicCCC_All_Scalar                     7.29ms	5.93ms	1.36ms		22.9%
- AnchoredNotFound_All                    14.8ms	13.5ms	1.33ms		9.8%
- DiceRollsInText_All_Scalar              39.9ms	38.6ms	1.31ms		3.4%
- BasicRangeCCC_All                       7.44ms	6.38ms	1.07ms		16.7%
- EmailLookaheadNoMatches_All             24ms	23ms	984µs		4.3%
- InvertedCCC_All_Scalar                  17.6ms	16.7ms	926µs		5.5%
- Numbers_All                             6.73ms	5.8ms	923µs		15.9%
- CaseInsensitiveCCC_All                  7.23ms	6.34ms	893µs		14.1%
- BasicRangeCCC_All_Scalar                7.29ms	6.4ms	884µs		13.8%
- CaseInsensitiveCCC_All_Scalar           7.22ms	6.35ms	871µs		13.7%
- EmailRFC_All                            64.8ms	64ms	820µs		1.3%
- EmailLookaheadNoMatches_All_Scalar      21.4ms	20.7ms	735µs		3.6%
- NotFound_All_Scalar                     6.82ms	6.18ms	643µs		10.4%
- NotFound_All                            7.67ms	7.2ms	468µs		6.5%
- MACAddress                              2.81ms	2.38ms	430µs		18.0%
- EmailRFC_All_Scalar                     45.4ms	45ms	425µs		0.9%
- IntersectionCCC_All                     22.2ms	21.8ms	415µs		1.9%
- SubtractionCCC_All_Scalar               21.4ms	21ms	384µs		1.8%
- AnchoredNotFound_First                  9.13ms	8.78ms	358µs		4.1%
- Numbers_All_Scalar                      5.66ms	5.34ms	319µs		6.0%
- IntersectionCCC_All_Scalar              22.2ms	21.9ms	318µs		1.5%
- Words_All                               12.7ms	12.4ms	316µs		2.5%
- LiteralSearchNotFound_All               6.71ms	6.44ms	271µs		4.2%
- EmailLookahead_All                      19.6ms	19.3ms	263µs		1.4%
- HangulSyllable_All                      6.92ms	6.66ms	261µs		3.9%
- MACAddress_Scalar                       2.49ms	2.25ms	232µs		10.3%
- IPv6Address                             2.78ms	2.56ms	223µs		8.7%
- IPv6Address_Scalar                      2.61ms	2.39ms	216µs		9.0%
- EmailLookahead_All_Scalar               17.3ms	17.1ms	205µs		1.2%
- LiteralSearch_All                       6.89ms	6.7ms	195µs		2.9%
- IPv4Address_Scalar                      2.24ms	2.06ms	186µs		9.0%
- HangulSyllable_All_Scalar               6.11ms	5.92ms	185µs		3.1%
- LiteralSearchNotFound_All_Scalar        5.68ms	5.51ms	172µs		3.1%
- GraphemeBreakNoCap_All_Scalar           2.99ms	2.83ms	161µs		5.7%
- GraphemeBreakNoCap_All                  3.1ms	2.95ms	149µs		5.0%
- EmailBuiltinCharacterClass_All_Scalar   10.3ms	10.2ms	147µs		1.4%
- ReluctantQuantWithTerminal_Whole        5.41ms	5.27ms	147µs		2.8%
- LiteralSearch_All_Scalar                5.87ms	5.73ms	145µs		2.5%
- ReluctantQuantWithTerminal_Whole_Scalar 5.34ms	5.21ms	123µs		2.4%
- Css_All_Scalar                          2.99ms	2.88ms	117µs		4.1%
- IPv4Address                             2.32ms	2.22ms	105µs		4.7%
- EagarQuantWithTerminal_Whole_Scalar     520µs	441µs	79.6µs		18.1%
- Css_All                                 3.31ms	3.23ms	76.2µs		2.4%
- DiceNotation                            4.58ms	4.51ms	75.1µs		1.7%
- EagarQuantWithTerminal_Whole            520µs	451µs	69.2µs		15.3%
- DiceNotation_Scalar                     4.33ms	4.26ms	65.5µs		1.5%
- Lines_All_Scalar                        1.73ms	1.67ms	64µs		3.8%
- Lines_All                               1.77ms	1.72ms	53.1µs		3.1%
=== Improvements =====================================================================
- EmailLookaheadList_Scalar               3.59ms	3.96ms	-370µs		-9.3%
- EmailBuiltinCharacterClass_All          10.5ms	10.7ms	-166µs		-1.6%
- AnchoredNotFound_First_Scalar           5.47ms	5.62ms	-153µs		-2.7%
- EmailLookaheadList                      3.81ms	3.87ms	-54.8µs		-1.4%