Refactor config class and reorganize image generation options

[lstein]

What type of PR is this? (check all applicable)

• [X Refactor
• Feature

Have you discussed this change with the InvokeAI team?

• Yes

Have you updated all relevant documentation?

• Yes

Description

Refactoring

This PR refactors invokeai.app.services.config to be easier to maintain by splitting off the argument, environment and init file parsing code from the InvokeAIAppConfig object. This will hopefully make it easier for people to find the place where the various settings are defined.

New Features

In collaboration with @StAlKeR7779 , I have renamed and reorganized the settings controlling image generation and model management to be more intuitive. The relevant portion of the init file now looks like this:

  Model Cache:
    ram: 14.5
    vram: 0.5
    lazy_offload: true
  Device:
    precision: auto
    device: auto
  Generation:
    sequential_guidance: false
    attention_type: auto
    attention_slice_size: auto
    force_tiled_decode: false

Key differences are:

1. Split Performance/Memory into Device, Generation and Model Cache
2. Added the ability to force the device. The value of this option is one of {auto, cpu, cuda, cuda:1, mps}
3. Added the ability to force the attention_type. Possible values are {auto, normal, xformers, sliced, torch-sdp}
4. Added the ability to force the attention_slice_size when sliced attention is in use. The value of this option is one of {auto, max} or an integer between 1 and 8.

@StAlKeR7779 Please confirm that I wired the attention_type and attention_slice_size configuration options to the diffusers backend correctly.

In addition, I have exposed the generation-related configuration options to the TUI:

Backward Compatibility

This refactor should be backward compatible with earlier versions of invokeai.yaml. If the user re-runs the invokeai-configure script, invokeai.yaml will be upgraded to the current format. Several configuration attributes had to be changed in order to preserve backward compatibility. These attributes been changed in the code where appropriate. For the record:

Old Name	Preferred New Name	Comment
max_cache_size	ram_cache_size
max_vram_cache	vram_cache_size
always_use_cpu	use_cpu	Better to check conf.device == "cpu"

[hipsterusername]

Added review but believe more are needed