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 71 lines in your changes missing coverage. Please review.

Project coverage is 91.85%. Comparing base (7d921e9) to head (bc17c17).

Files with missing lines	Patch %	Lines
vyper/cli/venom_main.py	0.00%	38 Missing ⚠️
vyper/cli/vyper_ir.py	0.00%	33 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #4398      +/-   ##
==========================================
- Coverage   92.07%   91.85%   -0.22%     
==========================================
  Files         120      120              
  Lines       17352    17393      +41     
  Branches     2938     2942       +4     
==========================================
  Hits        15977    15977              
- Misses        957      998      +41     
  Partials      418      418              

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