Have `otapreopt_chroot` bind-mount Bionic artifacts from the Runtime APEX.

Have `otapreopt_chroot` bind-mount Bionic artifacts (`linker(64)`,
`libc.so`, `libm.so`, `libdl.so`) from the Runtime APEX
(`/postinstall/apex/com.android.runtime`) into `/postinstall/bionic/`,
much the same way `init` sets up Bionic bind-mounts in the default
mount namespace.

Test: m otapreopt_chroot
Test: A/B OTA update test (asit/dexoptota/self_full).
Bug: 113373927
Bug: 120266448
Change-Id: Ie254a94ae35e62f88375bc89380456f15796566a