DPM: installKeyPair variant: caller can self-grant

If 'requestAccess' is true, the caller (either profile/device owner or a
designated certificate installer) will be granted usage of the keypair
on successful installation.

This has no security implications for a profile/device owner which would
already be able to self-grant. Delegated certificate installers did not
have this ability before.

This is only allowed at install-time- not afterward.

Bug: 24746231
Change-Id: Ia0ec290bb0bcde1d8137c188e2667cb7718dbfd7