IPEX support FP8 kvcache/softcap/slidingwindow (#3144)

* IPEX support FP8 kvcache

Signed-off-by: Wang, Yi A <yi.a.wang@intel.com>

* add kvcache dtype

Signed-off-by: Wang, Yi A <yi.a.wang@intel.com>

* add softcap and slidingwindow

Signed-off-by: Wang, Yi A <yi.a.wang@intel.com>

* kv scale in pageattn

Signed-off-by: Wang, Yi A <yi.a.wang@intel.com>

* remove triton installation, will be installed with torch

Signed-off-by: Wang, Yi A <yi.a.wang@intel.com>

* install xelink lib

Signed-off-by: Wang, Yi A <yi.a.wang@intel.com>

* softcap default -1.0

Signed-off-by: Wang, Yi A <yi.a.wang@intel.com>

* softcap default -1.0

Signed-off-by: Wang, Yi A <yi.a.wang@intel.com>

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Signed-off-by: Wang, Yi A <yi.a.wang@intel.com>