feat[ux]: improve hint for events kwarg upgrade

[charles-cooper]

follow-on commit to ebe3c0c. the hint in ebe3c0c is not specific to the user's source code, and it's a bit laborious for the user to match the call-site to the event def. this commit auto-generates the new call expression for the user to use.

What I did

How I did it

How to verify it

try compiling the following file:

from ethereum.ercs import IERC20

def foo():
    log IERC20.Transfer(msg.sender, msg.sender, 123)

Commit message

Commit message for the final, squashed PR. (Optional, but reviewers will appreciate it! Please see our commit message style guide for what we would ideally like to see in a commit message.)

Description for the changelog

Cute Animal Picture

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 53.43%. Comparing base (c02d2d8) to head (c4cc839).
Report is 4 commits behind head on master.

❗ There is a different number of reports uploaded between BASE (c02d2d8) and HEAD (c4cc839). Click for more details.

HEAD has 110 uploads less than BASE

Flag	BASE (c02d2d8)	HEAD (c4cc839)
	137	27

Additional details and impacted files

@@             Coverage Diff             @@
##           master    #4275       +/-   ##
===========================================
- Coverage   91.30%   53.43%   -37.88%     
===========================================
  Files         110      110               
  Lines       15764    15766        +2     
  Branches     3461     3462        +1     
===========================================
- Hits        14393     8424     -5969     
- Misses        935     6717     +5782     
- Partials      436      625      +189     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[charles-cooper]

there's something interesting going on with examples like

log Transfer(msg.sender, msg.sender, 1)  # 1 is only one character long

i guess mark_tokens() marks the wrong start+end position for the ast node.