Release GPU process memory after leaving for SD 1.5 and SD Turbo

[ibelem]

Fix #61

1. Add a "Release memory after leaving" switch in demo pages of SD 1.5 and SD Turbo, enabled by default
2. Run session.release() for browser beforeunload event

When go to new page in same tab with "Release memory after leaving" switch disabled

1. The memories of GPU process and blink (Tab) process are still high
2. When click browser "Back" button, users can run "generate image" directly without loading models and compiling models

When go to new page in same tab with "Release memory after leaving" switch enabled

1. The memory of GPU process will be released
2. The memory of blink (Tab) process is still high
3. When click browser "Back" button, users need to re-load and compile models then generate images

Note

It seems like the ONNX Runtime Web cannot release memory of blink (Tab) process.

• Onnxruntime Memory [Web]  onnxruntime#18165

@fs-eire WebAssembly memory cannot shrink. This means the wasm memory will keep the size of the peak memory usage, even if the code marks some part as "free".

• https://github.com/WebAssembly/memory-control/blob/main/proposals/memory-control/Overview.md

@fdwr PTAL

CC @Honry @mingmingtasd @huningxin

[fdwr]

Interesting - didn't know this memory was held. The $ change adds a bunch of noise that would be nicer as a separate CR (or at least separate commit), but the actual change looks fine to me, assuming my one concern is reassured.

[ibelem]

In the process of improving the memory code, I found that getElementById() and querySelector() were mixed used, and I couldn't help but change these codes. Will keep in mind the guidance of separating code formatting, refactoring, etc. from the original PR. :) @fdwr