the revive-explorer utility (#364)

A maintainable and more precise version of what was a hacky but useful
script, exploring the compilers YUL lowering unit.

It analyzes a given shared objects from the debug dump and outputs:
- The count of each YUL statement translated.
- A per YUL statement break-down of bytecode size contributed per.
- Estimated `yul-phaser` cost parameters.

Signed-off-by: Cyrill Leutwiler <bigcyrill@hotmail.com>

crates/explorer/README.md

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+# revive-explorer
+
+The `revive-explorer` is a helper utility for exploring the compilers YUL lowering unit.
+
+It analyzes a given shared objects from the debug dump and outputs:
+- The count of each YUL statement translated.
+- A per YUL statement break-down of bytecode size contributed per.
+- Estimated `yul-phaser` cost parameters.
+
+Example:
+
+```
+statements count:
+	block 532
+	Caller 20
+	Not 73
+	Gas 24
+	Shr 2
+    ...
+	Shl 259
+	SetImmutable 2
+	CodeSize 1
+	CallDataLoad 87
+	Return 56
+bytes per statement:
+	Or 756
+	CodeCopy 158
+	Log3 620
+	Return 1562
+	MStore 36128
+	...
+	ReturnDataCopy 2854
+	DataOffset 28
+	assignment 1194
+	Number 540
+	CallValue 4258
+yul-phaser parameters:
+	--break-cost 1
+	--variable-declaration-cost 3
+	--function-call-cost 8
+	--if-cost 4
+	--expression-statement-cost 6
+	--function-definition-cost 11
+	--switch-cost 3
+	--block-cost 1
+	--leave-cost 1
+	--assignment-cost 1
+```
+