Move `SourceDefinition` to `dbt/artifacts`

[QMalcolm]

resolves #9384

Problem

We are moving data artifacts to dbt/artifacts in a piecewise fashion. We needed to move SourceDefinition as part of that.

Solution

Moved data portion of SourceDefinition to dbt/artifacts (and all other classes that doing so required)

Checklist

• [X] I have read the contributing guide and understand what's expected of me
• [X] I have run this code in development and it appears to resolve the stated issue
• [X] This PR includes tests, or tests are not required/relevant for this PR
• [X] This PR has no interface changes (e.g. macros, cli, logs, json artifacts, config files, adapter interface, etc) or this PR has already received feedback and approval from Product or DX
• [X] This PR includes type annotations for new and modified functions

[codecov[bot]]

Codecov Report

Attention: 6 lines in your changes are missing coverage. Please review.

Comparison is base (581d856) 85.59% compared to head (e7fe26c) 87.97%. Report is 9 commits behind head on main.

Files	Patch %	Lines
...re/dbt/artifacts/resources/v1/source_definition.py	94.44%	3 Missing :warning:
core/dbt/contracts/graph/nodes.py	94.73%	2 Missing :warning:
core/dbt/artifacts/resources/v1/components.py	98.43%	1 Missing :warning:

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #9543      +/-   ##
==========================================
+ Coverage   85.59%   87.97%   +2.38%     
==========================================
  Files         167      168       +1     
  Lines       22164    22208      +44     
==========================================
+ Hits        18971    19538     +567     
+ Misses       3193     2670     -523     

Flag	Coverage Δ
integration	85.62% <96.57%> (+0.03%)	:arrow_up:
unit	61.93% <92.57%> (?)

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