Dummy lowering and node IDs

[g-r-a-n-t]

What was wrong?

We need some form of node identification for lowering. See #306.

This is an attempt to break up the mentioned PR.

How was it fixed?

• Added a lowering module that doesn't do anything yet.
• Renamed Spanned to Node and added an ID field.

fe/parser/src/node.rs

Lines 48 to 54 in 953b429

	#[derive(Serialize, Deserialize, Debug, PartialEq, Clone)]
	pub struct Node<T> {
	pub kind: T,
	#[serde(skip_serializing, skip_deserializing)]
	pub id: NodeId,
	pub span: Span,
	}

• Refactored broken code and tests. It's worth mentioning that the hacky spanned_expression helpers were removed.

ContextHarness was broken by this change, since it relies on adding attributes to the context via the span. I've disabled this with the feature fix-context-harness and will create an issue to fix this (if merging this with the failing tests sounds ok).

To-Do

• OPTIONAL: Update Spec if applicable

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

• Clean up commit history

[codecov-io]

Codecov Report

Merging #315 (816913a) into master (b870477) will decrease coverage by 1.12%.
The diff coverage is 95.17%.

@@            Coverage Diff             @@
##           master     #315      +/-   ##
==========================================
- Coverage   93.72%   92.60%   -1.13%     
==========================================
  Files          56       56              
  Lines        3986     3774     -212     
==========================================
- Hits         3736     3495     -241     
- Misses        250      279      +29     

Impacted Files	Coverage Δ
analyzer/src/errors.rs	83.33% <ø> (ø)
analyzer/src/traversal/assignments.rs	96.66% <ø> (ø)
analyzer/src/traversal/declarations.rs	96.77% <ø> (ø)
compiler/src/yul/mappers/assignments.rs	75.00% <ø> (-22.83%)	⬇️
parser/src/lib.rs	100.00% <ø> (ø)
parser/src/tokenizer/tokenize.rs	100.00% <ø> (ø)
analyzer/src/traversal/utils.rs	77.77% <50.00%> (ø)
compiler/src/yul/utils.rs	87.87% <50.00%> (-5.88%)	⬇️
parser/src/ast_traits.rs	81.52% <72.22%> (+0.87%)	⬆️
compiler/src/lib.rs	90.00% <80.00%> (+1.11%)	⬆️
... and 26 more

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[cburgdorf]

What a huge diff! Good you separated it from the coming changes. It looks good. I don't like the disabled tests but if you say you'll track it with an issue and make sure to get them re-enabled as soon as possible then I'm ok with it given the complexity of the overall task.