[Common] Extract APIs for plug-in developers from tensor_common

[Common] Extract APIs for plug-in developers from tensor_common

Since we do not export tensor_common anymore, plug-in developers outside
our repository cannot use typedefed data types and mandatory functions
to implement NNStreamer extension plug-ins. In order to handle such
issue, this patch extracts types and functions can be regarded as APIs
from tensor_common. Note that only subset of all APIs which the plugin
developers would need has been currently extracted.

Signed-off-by: Wook Song <wook16.song@samsung.com>