* add int8 definitions
* packing vulkan int8/int32, quantize vulkan
* vulkan dequantize
* requantize vulkan

* fix pyncnn build

vkimagemat was originally used as a mat storage in the hope of improving performance on old adreno gpus, but in fact it is slower than the cpu in most cases and is no longer suitable for the latest adreno architecture and large shapes

* check image fp16

* zfh zvfh xtheadvector infra
* dispatch for rvv and xtheadvector
* dispatch for non-vector zfh
* port xtheadvector recp rsqrt trunc
* general rvv gemm
* c906 and c910 ci
* old tuple code clean
* update riscv64 ci
* update build doc
* drop old th1520 toolchain

* fix potential fp16s bf16s conflicts on armv7 vfpv4

* but prefer fp16 on armv8.2

* skip mips loongarch riscv oom test atm

* test softmax oom

* promote vfpv4 for auto fp16 storage conversion

* always report neon and vfpv4 for arm64

* create layer decoupled
* no more virtual public
* allow build test with shared library
* decouple cpu vulkan
* drop old scripts