chore: improve syntax error messages

[tserg]

What I did

Fix #3865

The exception now displays as:

vyper.exceptions.SyntaxException: invalid syntax (<unknown>, line 3)

  line 3:31 
       2 def foo():
  ---> 3     s: String[2] = staticcall staticcall concat('a', 'b')
  --------------------------------------^
       4     return

How I did it

How to verify it

Not sure how to go about writing a test for this

Commit message

chore: improve syntax error handling

This PR improves the handling of syntax errors by obscuring
the underlying exception from the python parser.

Description for the changelog

Cute Animal Picture

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 86.36%. Comparing base (f8d4b97) to head (fc261ce).

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Additional details and impacted files

@@           Coverage Diff           @@
##           master    #3885   +/-   ##
=======================================
  Coverage   86.36%   86.36%           
=======================================
  Files          92       92           
  Lines       14024    14024           
  Branches     3081     3081           
=======================================
  Hits        12112    12112           
  Misses       1484     1484           
  Partials      428      428           

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[charles-cooper]

thanks!