feat(llama.cpp): do not specify backends to autoload and add llama.cpp variants (#2232)

* feat(initializer): do not specify backends to autoload

We can simply try to autoload the backends extracted in the asset dir.
This will allow to build variants of the same backend (for e.g. with different instructions sets),
so to have a single binary for all the variants.

Signed-off-by: mudler <mudler@localai.io>

* refactor(prepare): refactor out llama.cpp prepare steps

Make it so are idempotent and that we can re-build

Signed-off-by: mudler <mudler@localai.io>

* [TEST] feat(build): build noavx version along

Signed-off-by: mudler <mudler@localai.io>

* build: make build parallel

Signed-off-by: Ettore Di Giacinto <mudler@localai.io>

* build: do not override CMAKE_ARGS

Signed-off-by: Ettore Di Giacinto <mudler@localai.io>

* build: add fallback variant

Signed-off-by: Ettore Di Giacinto <mudler@localai.io>

* Fixups

Signed-off-by: Ettore Di Giacinto <mudler@localai.io>

* fix(huggingface-langchain): fail if no token is set

Signed-off-by: Ettore Di Giacinto <mudler@localai.io>

* fix(huggingface-langchain): rename

Signed-off-by: Ettore Di Giacinto <mudler@localai.io>

* fix: do not autoload local-store

Signed-off-by: Ettore Di Giacinto <mudler@localai.io>

* fix: give priority between the listed backends

Signed-off-by: Ettore Di Giacinto <mudler@localai.io>

---------

Signed-off-by: mudler <mudler@localai.io>
Signed-off-by: Ettore Di Giacinto <mudler@localai.io>