fix: self in pure functions

[tserg]

What I did

Fix for #3021

How I did it

Check for standalone accesses to self by filtering out Name nodes with an ancestor that is not an Attribute node.

How to verify it

See test

Commit message

fix: access to `self` in pure functions

Description for the changelog

Disable access to self in pure functions

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[codecov-commenter]

Codecov Report

Merging #3027 (fb12cdc) into master (38eb512) will decrease coverage by 21.13%.
The diff coverage is 100.00%.

@@             Coverage Diff             @@
##           master    #3027       +/-   ##
===========================================
- Coverage   88.30%   67.16%   -21.14%     
===========================================
  Files          97       97               
  Lines       10948    10947        -1     
  Branches     2587     2523       -64     
===========================================
- Hits         9668     7353     -2315     
- Misses        831     2944     +2113     
- Partials      449      650      +201     

Impacted Files	Coverage Δ
vyper/semantics/validation/local.py	61.56% <100.00%> (-29.66%)	⬇️
vyper/builtin_functions/utils.py	0.00% <0.00%> (-100.00%)	⬇️
vyper/ir/s_expressions.py	5.88% <0.00%> (-88.24%)	⬇️
vyper/ast/natspec.py	12.34% <0.00%> (-86.42%)	⬇️
vyper/cli/utils.py	16.66% <0.00%> (-71.43%)	⬇️
vyper/compiler/utils.py	30.00% <0.00%> (-70.00%)	⬇️
vyper/cli/vyper_json.py	9.44% <0.00%> (-69.59%)	⬇️
vyper/compiler/output.py	27.74% <0.00%> (-61.26%)	⬇️
vyper/semantics/validation/data_positions.py	36.55% <0.00%> (-54.84%)	⬇️
vyper/builtin_functions/convert.py	38.35% <0.00%> (-52.69%)	⬇️
... and 53 more

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