Add analyzer checks for shadowing of built-ins and generic arg lists where they don't belong

[sbillig]

What was wrong?

The analyzer allowed things like:

type u8 = u256
let u256: u8 = 10
fn u8(u8: u256) -> u8:
let keccak256: u256 = keccak256(x)
let x: u256 = u256<1, 2, 3>(10)

How was it fixed?

Added more checks to type, function, and var defs. This implementation isn't super satisfying; I was able to consolidate some duplicate logic, but we still have to perform this kind of check in 3 places, which doesn't seem ideal.

To-Do

• Add entry to the release notes (may forgo for trivial changes)

• Clean up commit history

[codecov-commenter]

Codecov Report

Merging #539 (2d8cd99) into master (8ee4ed7) will decrease coverage by 0.68%.
The diff coverage is 77.91%.

@@            Coverage Diff             @@
##           master     #539      +/-   ##
==========================================
- Coverage   87.91%   87.23%   -0.69%     
==========================================
  Files          87       88       +1     
  Lines        5653     5931     +278     
==========================================
+ Hits         4970     5174     +204     
- Misses        683      757      +74     

Impacted Files	Coverage Δ
crates/analyzer/src/errors.rs	80.95% <ø> (ø)
crates/analyzer/src/traversal/assignments.rs	66.66% <ø> (ø)
crates/analyzer/src/namespace/items.rs	89.78% <40.00%> (-1.38%)	⬇️
crates/parser/src/ast.rs	71.42% <69.68%> (+7.49%)	⬆️
crates/analyzer/src/namespace/scopes.rs	81.51% <73.33%> (-1.35%)	⬇️
crates/analyzer/src/traversal/utils.rs	81.81% <82.35%> (-2.19%)	⬇️
crates/analyzer/src/traversal/types.rs	94.36% <96.61%> (-1.09%)	⬇️
crates/analyzer/src/builtins.rs	100.00% <100.00%> (ø)
crates/analyzer/src/db/queries/contracts.rs	97.76% <100.00%> (+0.12%)	⬆️
crates/analyzer/src/db/queries/module.rs	100.00% <100.00%> (ø)
... and 7 more

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[g-r-a-n-t]

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