feat: 2.0.9 Rough support for more kernels

[jgabaut]

Added

• Rough support for anvilPy kern
  • Improves [FEATURE] Add support for anvilPy kern #104
• Rough support for custom kern
  • Improves [FEATURE] Add support for more project types #110
  • Adds new key to stego.lock:

    [anvil]
    kern = "custom"
    custombuilder="./foo"
    version = "2.1.0"

• Using either of the new kern option requires running as 2.1.0, which currently is not accepted as a direct -a argument
• Add -Z to pass custom CFLAGS
  • Avoids reading passed CFLAGS var
  • Closes [BUG] Single file build op fails when CFLAGS is not set #123

Changed

• Refactor introducing ambosoC_build_step(), ambosoC_delete_step() making init, purge ops iterative
  • Improves [FEATURE] Drop recursive logic to align with invil #106
• Flags expecting an argument refuse args starting with -
  • Pass AMBOSO_ALLOW_FLAGS_HYPHEN_ARG >0 to skip this check
• Try reading AMBOSO_CONFIG_ARG_ISFILE to use -C with flags directly
  • Setting it to 0 enables the new, backwards incompatible behaviour
• Fix echo_active_flags() reporting -C incorrectly
  • Closes [BUG] echo_active_flags() reports the wrong flag for -Y #124
• Try using HEAD when -G receives an invalid tag