Implement intermediate loading for ISQ on CPU

[EricLBuehler]

Refs and closes #215.

Api addition

• DeviceMapper
  • All at-loading-time methods have loading_isq parameter
  • Add fn set_nm_device<'a>(&self, varbuilder: VarBuilder<'a>, loading_isq: bool) -> VarBuilder<'a> for mapping non-mapped layers.

[github-actions]

Code Metrics Report

  ───────────────────────────────────────────────────────────────────────────────
Language                 Files     Lines   Blanks  Comments     Code Complexity
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Rust                        70     22353     1540       502    20311       1261
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Total                       70     22353     1540       502    20311       1261
───────────────────────────────────────────────────────────────────────────────
Estimated Cost to Develop 37,842
Estimated Schedule Effort 11.593247 months
Estimated People Required 4.887919
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Processed 738098 bytes, 0.738 megabytes (SI)
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[EricLBuehler]

Looks good.