js: Add stats and override options (#348)

- Add `RESOLC_BIN` env variable to force use a binary compiler instead
of the wasm
- Add `--diff-stats` options to print file path 

e.g

```
~/github/redstone-oracles-monorepo main*
❯ npx @parity/resolc@latest --diff-stats \
  --base-path . \
  --include-path node_modules \
  --bin packages/evm-connector/contracts/samples/SampleWithEvents.sol
┌─────────┬──────────────────────────────────────────────────────────────────────────┬───────────────────────────────┬────────────┬────────────┬───────────┐
│ (index) │ file                                                                     │ contract                      │ polkavm    │ bin        │ diff      │
├─────────┼──────────────────────────────────────────────────────────────────────────┼───────────────────────────────┼────────────┼────────────┼───────────┤
│ 0       │ 'packages/evm-connector/contracts/core/CalldataExtractor.sol'            │ 'CalldataExtractor'           │ '4.31 kB'  │ '2.53 kB'  │ '70.12%'  │
│ 1       │ 'packages/evm-connector/contracts/core/RedstoneConstants.sol'            │ 'RedstoneConstants'           │ '0.80 kB'  │ '0.17 kB'  │ '368.18%' │
│ 2       │ 'packages/evm-connector/contracts/core/RedstoneDefaultsLib.sol'          │ 'RedstoneDefaultsLib'         │ '0.90 kB'  │ '0.31 kB'  │ '189.06%' │
│ 3       │ 'packages/evm-connector/contracts/libs/BitmapLib.sol'                    │ 'BitmapLib'                   │ '0.90 kB'  │ '0.31 kB'  │ '189.06%' │
│ 4       │ 'packages/evm-connector/contracts/libs/NumericArrayLib.sol'              │ 'NumericArrayLib'             │ '0.90 kB'  │ '0.31 kB'  │ '189.06%' │
│ 5       │ 'packages/evm-connector/contracts/libs/SignatureLib.sol'                 │ 'SignatureLib'                │ '0.90 kB'  │ '0.31 kB'  │ '189.06%' │
│ 6       │ 'packages/evm-connector/contracts/mocks/RedstoneConsumerNumericMock.sol' │ 'RedstoneConsumerNumericMock' │ '13.62 kB' │ '10.17 kB' │ '33.96%'  │
│ 7       │ 'packages/evm-connector/contracts/samples/SampleWithEvents.sol'          │ 'SampleWithEvents'            │ '29.34 kB' │ '15.60 kB' │ '88.03%'  │
└─────────┴──────────────────────────────────────────────────────────────────────────┴───────────────────────────────┴────────────┴────────────┴───────────┘
```

js/resolc/src/index.ts

@@ -50,11 +50,7 @@ export function resolveInputs(sources: SolcInput): SolcInput {
     language: 'Solidity',
     sources,
     settings: {
-      outputSelection: {
-        '*': {
-          '*': ['evm.bytecode.object'],
-        },
-      },
+      outputSelection: {}, // no outputs requested, only resolves imports
     },
   }
 
@@ -106,7 +102,7 @@ export async function compile(
       enabled: true,
       runs: 200,
     },
-    bin,
+    bin = process.env.RESOLC_BIN,
   } = option
 
   const input = JSON.stringify({