CustomCommandManager + CustomCommandManagerSession to use auto-expandable maps

[TalZaccai]

• Implementing ExpandableMap struct which maps a specified range of IDs to an array which doubles in size as needed.
• Switching CustomCommandManager & CustomCommandManagerSession to use ExpandableMap instead of using set-sized arrays.
• Adding tests to RespCustomCommandTests to test registration of multiple string commands, object commands, transactions and procedures.

Note: this relates to closed issue #834, which was addressed by temporary fix in PR #836.

Benchmark results:

main:

Method	Params	Mean	Error	StdDev	Gen0	Allocated
CustomRawStringCommand	ACL	409.1 us	7.60 us	7.11 us	-	-
CustomObjectCommand	ACL	1,061.6 us	17.22 us	16.11 us	1.9531	24002 B
CustomTransaction	ACL	1,738.7 us	31.31 us	49.66 us	-	2 B
CustomProcedure	ACL	1,264.8 us	14.86 us	13.90 us	-	2 B
CustomRawStringCommand	AOF	414.0 us	4.80 us	4.49 us	-	-
CustomObjectCommand	AOF	1,227.9 us	16.35 us	15.30 us	1.9531	24002 B
CustomTransaction	AOF	1,967.2 us	6.12 us	5.43 us	-	4 B
CustomProcedure	AOF	1,678.9 us	27.81 us	38.99 us	-	2 B
CustomRawStringCommand	None	403.5 us	7.81 us	7.31 us	-	-
CustomObjectCommand	None	1,110.4 us	21.81 us	31.28 us	1.9531	24002 B
CustomTransaction	None	1,732.3 us	12.80 us	9.99 us	-	2 B
CustomProcedure	None	1,229.2 us	24.41 us	21.64 us	-	2 B

PR #848:

Method	Params	Mean	Error	StdDev	Gen0	Allocated
CustomRawStringCommand	ACL	411.1 us	1.74 us	1.63 us	-	-
CustomObjectCommand	ACL	1,105.2 us	2.20 us	1.95 us	1.9531	24002 B
CustomTransaction	ACL	1,668.7 us	20.38 us	19.07 us	-	2 B
CustomProcedure	ACL	1,205.2 us	1.04 us	0.93 us	-	2 B
CustomRawStringCommand	AOF	394.8 us	1.59 us	1.33 us	-	-
CustomObjectCommand	AOF	1,221.4 us	3.30 us	2.92 us	1.9531	24002 B
CustomTransaction	AOF	1,861.3 us	3.48 us	3.08 us	-	2 B
CustomProcedure	AOF	1,632.2 us	24.00 us	22.45 us	-	2 B
CustomRawStringCommand	None	402.2 us	1.39 us	1.30 us	-	-
CustomObjectCommand	None	1,108.0 us	1.65 us	1.46 us	1.9531	24002 B
CustomTransaction	None	1,646.6 us	5.77 us	5.11 us	-	2 B
CustomProcedure	None	1,209.7 us	2.49 us	1.95 us	-	2 B