Preparatory changes for better incremental build support with the code generators

[aormerod-gs]

Preparatory changes for better incremental build support with the code generators.

• Add support for last modified information on code storage
• Update generators to support checking file modification times to skip where possible

[github-actions[bot]]

Test Results

   538 files  ±0     538 suites  ±0   22m 9s :stopwatch: -10s 3 938 tests ±0  3 906 :heavy_check_mark: ±0  32 :zzz: ±0  0 :x: ±0  5 255 runs  ±0  5 223 :heavy_check_mark: ±0  32 :zzz: ±0  0 :x: ±0 

Results for commit ec8e3333. ± Comparison against base commit 2301fac0.