Prompt cache

[saddam213]

Cache tensors from text_encoders to speed up generation when the same prompt is used

Issue: #3

[saddam213]

InputImage should also be cached to avoid running the vae_encoder for the same image

[saddam213]

Good performance improvements for subsequent calls, quickly tested both the TextToImage and ImageToImage

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TextToImage - No Cache

TextToImage: 2973.1986ms
TextToImage: 785.7539ms
TextToImage: 462.6996ms
TextToImage: 546.9946ms
TextToImage: 247.2857ms
TextToImage: 562.5287ms
TextToImage: 425.6608ms
TextToImage: 215.4142ms
TextToImage: 306.3986ms
TextToImage: 208.544ms

TextToImage - Cached

TextToImage: 2867.7748ms
TextToImage: 218.2006ms
TextToImage: 216.4643ms
TextToImage: 204.0963ms
TextToImage: 302.4757ms
TextToImage: 468.3393ms
TextToImage: 194.7951ms
TextToImage: 184.639ms
TextToImage: 191.3407ms
TextToImage: 195.7907ms

ImageToImage - No Cache

ImageToImage: 4096.9154ms
ImageToImage: 597.0858ms
ImageToImage: 732.4881ms
ImageToImage: 600.2822ms
ImageToImage: 301.5615ms
ImageToImage: 729.3553ms
ImageToImage: 336.8014ms
ImageToImage: 444.0248ms
ImageToImage: 330.6012ms
ImageToImage: 470.1376ms

ImageToImage - Cached

ImageToImage: 4044.009ms
ImageToImage: 320.9691ms
ImageToImage: 208.1214ms
ImageToImage: 186.4001ms
ImageToImage: 497.2423ms
ImageToImage: 183.8987ms
ImageToImage: 193.4917ms
ImageToImage: 204.4805ms
ImageToImage: 188.0385ms
ImageToImage: 196.0874ms