* 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