Improve visibility of subsequently defined contracts

[cburgdorf]

What was wrong?

This superseded #294

If two contracts are defined in a module, only the second contract can see the interface of the first.

e.g.

# can't see Bar
contract Foo:
   ...

# can see Foo
contract Bar:
   ...

How was it fixed?

1. Contract analysis is split into multiple passes:
   1 The first pass collects contracts with their function definition but does not inspect function bodies and contract fields
   2. Once every contract was analyzed, we analyze the function bodies and contract field of each contract in a subsequent pass

2. Because the module scope now contains all contracts it needs a way to filter out the main contract when it is aggregating external_contracts. To do that, name was added to ContractScope (we also have name for BlockScope so there's a precedence for having the name as a scope identifier) so that we can filter out the "self contract" upon aggregation.

3. The Uniswap demo was updated to use that feature

This PR doesn't yet address issue #299 though.

[cburgdorf]

@g-r-a-n-t since fields aren't in the public API of contracts it omitting them here doesn't interfere with the contract representation in the scope. But by delaying analysis to the next pass we can at least support referring to subsequent contracts in contract fields.

[cburgdorf]

@g-r-a-n-t Here's my second attempt which removes all the machinery to manage partial representation of contracts. I created #299 to track the issue with not being able to use subsequently defined contract types in function definitions.

[codecov-io]

Codecov Report

Merging #298 (bf46956) into master (0d7b317) will increase coverage by 0.01%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #298      +/-   ##
==========================================
+ Coverage   93.44%   93.45%   +0.01%     
==========================================
  Files          56       56              
  Lines        3997     4005       +8     
==========================================
+ Hits         3735     3743       +8     
  Misses        262      262              

Impacted Files	Coverage Δ
analyzer/src/traversal/contracts.rs	100.00% <ø> (ø)
analyzer/src/lib.rs	90.22% <100.00%> (+0.14%)	⬆️
analyzer/src/namespace/scopes.rs	95.28% <100.00%> (+0.02%)	⬆️
analyzer/src/traversal/assignments.rs	96.66% <100.00%> (ø)
analyzer/src/traversal/declarations.rs	96.77% <100.00%> (ø)
analyzer/src/traversal/expressions.rs	93.05% <100.00%> (ø)
analyzer/src/traversal/functions.rs	97.41% <100.00%> (ø)
analyzer/src/traversal/module.rs	100.00% <100.00%> (ø)

---

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 0d7b317...bf46956. Read the comment docs.