SVE support for exponential functions

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This PR introduces support for SVE(Scalable Vector Extensions) kernels for the exponential on the Arm architecture.

Verifying Features

This PR contains the SVE implementation of the exponential function used to compute the Activation and Softmax functions.
The values of the NEON and SVE implementations were compared sequentially, and it was confirmed that the values always roughly same.
We also verified that the perplexity matches between the NEON and SVE implementations.

Orginal(NEON)	This PR(SVE)
6.6741 +/- 0.04126	6.6732 +/- 0.04125

performance check

Performance was measured with FX700.
Performance is improved as follows. The value is ggml_vec_soft_max_f32's cycles. (ggml_v_expf symbol is striped by optimization.)

batch size	Original(NEON)	This PR(SVE)	Ratio
1	185,895,707	73,095,311	2.54
2	632,556,068	220,198,078	2.87
4	2,150,478,150	716,458,163	3.00
8	8,290,580,604	2,559,182,187	3.24

The command used to measure the performance is

llama-batched --model ${PATH_TO_MODEL} --prompt 'AI is going to' --parallel 8 --predict 128 --seed 0 --threads 12