Add a set of bootstrap methods to ConstantBootstraps for retrieving array elements of various array types.

This could be useful for instance when a dynamic constant resolves to an array, and specific elements need to be loaded for downstream dynamic constants. (for example, a hidden class defined with class data, which is an Object[], and needs to load elements from that array into the constant pool as well, for fast access).

The current solution for clients is either to define a custom bootstrap method, or to create an array element getter method handle, and use that in a downstream condy (somewhat convoluted).