Make wasmi CLI print exported functions if func_name arg is missing

[Robbepop]

Before this change users had to provide a non-existing func name in order for the wasmi CLI to print out all exported function names such as wasmi_cli fibonacci.wat foo.

> wasmi_cli fibonacci.wat
Error: missing function name argument for fibonacci.wat

The Wasm module exports the following functions:

 - fn fib_recursive(i64) -> i64
 - fn fib_iterative(i64) -> i64

[paritytech-cicd-pr]

BENCHMARKS

	NATIVE			WASMTIME
BENCHMARK	MASTER	PR	DIFF	MASTER	PR	DIFF	WASMTIME OVERHEAD
execute/ bare_call_0	1.01ms	1.01ms	🟢 0.13%	980.81µs	936.30µs	🟢 -4.40%	🟢 -7%
execute/ bare_call_0/typed	526.92µs	520.58µs	🟢 -1.46%	448.84µs	452.45µs	⚪ 0.92%	🟢 -13%
execute/ bare_call_1	1.09ms	1.08ms	🟢 -0.12%	1.21ms	1.17ms	🔴 -2.56%	🟢 8%
execute/ bare_call_16	2.23ms	2.19ms	⚪ -1.62%	4.60ms	4.77ms	🔴 3.88%	🔴 118%
execute/ bare_call_16/typed	1.32ms	1.30ms	⚪ -0.92%	2.25ms	2.28ms	🔴 1.56%	🟡 75%
execute/ bare_call_1/typed	645.97µs	603.81µs	🟢 -6.15%	750.94µs	745.91µs	⚪ -0.73%	🟢 24%
execute/ bare_call_4	1.21ms	1.19ms	🔴 -2.44%	1.94ms	1.92ms	⚪ -1.11%	🟡 61%
execute/ bare_call_4/typed	623.91µs	642.18µs	🔴 3.23%	896.78µs	892.64µs	⚪ -0.43%	🟢 39%
execute/ br_table	629.88µs	627.25µs	⚪ -1.31%	978.50µs	978.44µs	⚪ -0.02%	🟡 56%
execute/ count_until	682.33µs	682.00µs	⚪ -0.30%	2.21ms	2.19ms	⚪ -0.82%	🔴 221%
execute/ factorial_iterative	305.47µs	303.74µs	⚪ -0.69%	868.16µs	864.91µs	⚪ -0.27%	🔴 185%
execute/ factorial_recursive	624.20µs	610.29µs	🟢 -2.10%	1.33ms	1.30ms	🟢 -2.24%	🔴 113%
execute/ fib_iterative	1.43ms	1.43ms	⚪ -0.09%	4.73ms	4.62ms	🟢 -2.45%	🔴 223%
execute/ fib_recursive	6.14ms	5.76ms	🟢 -5.85%	12.10ms	12.00ms	⚪ -0.76%	🔴 108%
execute/ global_bump	978.63µs	977.78µs	⚪ -0.02%	3.13ms	3.15ms	⚪ 0.75%	🔴 223%
execute/ global_const	717.60µs	717.55µs	⚪ 0.00%	2.57ms	2.61ms	🔴 1.70%	🔴 263%
execute/ host_calls	28.88µs	28.68µs	⚪ -0.79%	42.63µs	42.38µs	⚪ -0.44%	🟢 48%
execute/ memory_fill	1.28ms	1.28ms	⚪ 0.02%	4.19ms	4.19ms	⚪ 0.10%	🔴 227%
execute/ memory_sum	1.27ms	1.27ms	⚪ 0.01%	4.24ms	4.24ms	⚪ 0.05%	🔴 234%
execute/ memory_vec_add	2.64ms	2.71ms	⚪ 1.81%	8.54ms	8.50ms	⚪ -0.39%	🔴 213%
execute/ recursive_is_even	1.13ms	1.11ms	⚪ -1.64%	2.11ms	2.10ms	⚪ -0.62%	🟡 89%
execute/ recursive_ok	143.24µs	144.52µs	⚪ 1.02%	297.94µs	297.58µs	⚪ -0.22%	🔴 106%
execute/ recursive_scan	187.61µs	178.68µs	🟢 -4.72%	386.85µs	393.53µs	🔴 1.94%	🔴 120%
execute/ recursive_trap	14.11µs	14.33µs	🔴 1.65%	30.59µs	30.15µs	⚪ -1.86%	🔴 110%
execute/ regex_redux	544.16µs	541.35µs	⚪ -0.48%	1.53ms	1.51ms	🟢 -1.25%	🔴 179%
execute/ rev_complement	498.08µs	497.63µs	⚪ 0.12%	1.52ms	1.52ms	⚪ 0.35%	🔴 206%
execute/ tiny_keccak	377.91µs	375.10µs	⚪ -1.01%	1.22ms	1.21ms	⚪ -0.58%	🔴 222%
execute/ trunc_f2i	919.56µs	911.78µs	⚪ -0.85%	2.51ms	2.51ms	⚪ -0.38%	🔴 175%
instantiate/ wasm_kernel	58.48µs	59.74µs	⚪ 2.28%	95.41µs	72.88µs	🟢 -23.75%	🟢 22%
translate/ erc1155	202.64µs	205.10µs	⚪ 1.15%	407.35µs	401.14µs	🟢 -1.47%	🟡 96%
translate/ erc20	99.99µs	99.66µs	⚪ -0.62%	199.59µs	198.04µs	⚪ -0.84%	🟡 99%
translate/ erc721	145.23µs	143.58µs	⚪ -3.35%	289.49µs	285.24µs	🟢 -1.56%	🟡 99%
translate/ spidermonkey	0.00ns	0.00ns	⚪ -0.06%	0.00ns	0.00ns	🟢 -1.47%	🟢 0%
translate/ wasm_kernel	3.80ms	3.78ms	⚪ -0.57%	7.71ms	7.58ms	🟢 -1.84%	🟡 100%

Link to pipeline

[codecov-commenter]

Codecov Report

Merging #579 (9853818) into master (d799789) will decrease coverage by 0.11%.
The diff coverage is 0.00%.

@@            Coverage Diff             @@
##           master     #579      +/-   ##
==========================================
- Coverage   80.07%   79.96%   -0.12%     
==========================================
  Files          78       78              
  Lines        6320     6329       +9     
==========================================
  Hits         5061     5061              
- Misses       1259     1268       +9     

Impacted Files	Coverage Δ
crates/cli/src/main.rs	0.00% <0.00%> (ø)

📣 We’re building smart automated test selection to slash your CI/CD build times. Learn more