Deprecate KeyChain.isBoundKeyAlgorithm.

This is bad API. There was never a guarantee that when this method
returns true for a key algorithm (e.g., RSA or EC), then all keys of
that type will be imported into secure hardware. For example, the
secure hardware may reject a key if it's of unsupported size or uses
an unsupported public exponent or EC curve. In that case, the key
will be imported into keystore/KeyChain without being backed by secure
hardware.

Bug: 18088752
Change-Id: I8daa574a2e703a347d09d93401cd1ea2d0162ed9