Test contract member intialization

[turbolent]

Closes #312

Description

Accessing fields before they are initialized does not cause a crash anymore since #768.

Add additional tests for this particular use-case, accessing contract fields before they are initialized.

When adding the tests I realized that in tests, the initializer of a contract is not called.
This is due to an optimization we added a while ago to only lazily load a contract value.
As most tests rely on contract declarations and thus contract initializers being evaluated eagerly, I added this to the parseCheckAndInterpret helper function that is used by all interpreter tests.

---

• Targeted PR against master branch
• Linked to Github issue with discussion and accepted design OR link to spec that describes this work
• Code follows the standards mentioned here
• Updated relevant documentation
• Re-reviewed Files changed in the Github PR explorer
• Added appropriate labels

[codecov-commenter]

Codecov Report

Merging #931 (e028729) into master (c84693a) will increase coverage by 34.10%.
The diff coverage is 83.33%.

@@             Coverage Diff             @@
##           master     #931       +/-   ##
===========================================
+ Coverage   40.09%   74.20%   +34.10%     
===========================================
  Files         254      267       +13     
  Lines       32206    33001      +795     
===========================================
+ Hits        12913    24487    +11574     
+ Misses      18406     7386    -11020     
- Partials      887     1128      +241     

Flag	Coverage Δ
unittests	74.20% <83.33%> (+34.10%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
runtime/interpreter/interpreter.go	90.11% <75.00%> (+68.40%)	⬆️
runtime/interpreter/interpreter_invocation.go	96.22% <100.00%> (+47.16%)	⬆️
runtime/interpreter/interpreter_statement.go	88.63% <100.00%> (+68.18%)	⬆️
runtime/cmd/minifier/minifier.go
runtime/tests/checker/utils.go
runtime/errors/errors.go	0.00% <0.00%> (ø)
fixedpoint/parse.go	93.50% <0.00%> (ø)
runtime/compiler/ir/valtype_string.go	0.00% <0.00%> (ø)
vm/vm.go	55.17% <0.00%> (ø)
runtime/compiler/wasm/gen/main.go	0.00% <0.00%> (ø)
... and 177 more

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update c84693a...e028729. Read the comment docs.