refactor[tool]: refactor venom and fang CLI parsing

[pcaversaccio]

What I did

This PR refactors the venom and fang CLI parsing and improves the error handling.

How I did it

Played around with the CLI and saw some opportunities for improvements.

How to verify it

For fang, use the file test.lll:

(with x pass
 (with y pass
  (with baseUnit pass
   (div (with t (mul x y) (seq (assert (eq (div t x) y)) t)) baseUnit)
    )))

For venom, use the file test.venom:

function entry {
    entry:
        invoke @check_cv
        jmp @wow
    wow:
        mstore 0, 1
        return 0, 32
}
function check_cv {
    check_cv:
        %1 = callvalue
        %2 = param
        jnz @no_value, @has_value, %1
    no_value:
        ret %2
    has_value:
        revert 0, 0
}
[data]

For standard input, use this:

echo "function start { start: %1 = callvalue jnz @fine, @has_callvalue, %1 fine: %2 = calldataload 4 %4 = add %2, 279387 return %2, %4 has_callvalue: revert 0, 0 } [data]" | venom --stdin

Commit message

this commit refactors the `venom` and `fang` CLI parsing.
it improves error handling and updates the help message. 

Description for the changelog

refactor[tool]: refactor venom and fang CLI parsing

Cute Animal Picture

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 69 lines in your changes missing coverage. Please review.

Project coverage is 52.66%. Comparing base (537313b) to head (68c4ce0).

Files with missing lines	Patch %	Lines
vyper/cli/venom_main.py	0.00%	36 Missing ⚠️
vyper/cli/vyper_ir.py	0.00%	33 Missing ⚠️

❗ There is a different number of reports uploaded between BASE (537313b) and HEAD (68c4ce0). Click for more details.

HEAD has 170 uploads less than BASE

Flag	BASE (537313b)	HEAD (68c4ce0)
	200	30

Additional details and impacted files

@@             Coverage Diff             @@
##           master    #4398       +/-   ##
===========================================
- Coverage   91.11%   52.66%   -38.46%     
===========================================
  Files         115      115               
  Lines       16225    16264       +39     
  Branches     2728     2732        +4     
===========================================
- Hits        14784     8566     -6218     
- Misses       1006     7067     +6061     
- Partials      435      631      +196     

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