binder: Use StaticString16 for interface descriptors

Binder interface descriptors is one of the biggest sources of static
constructors.  Use the newly implemented StaticString16 to avoid
runtime construction.

Bug: 138856262
Test: Build and boot cuttlefish.
Test: Check interface descriptors now reside in .data sections.
Test: Measure the memory usage of libraries affected by this change,
      including .data, .data.rel.ro, and .bss sections, on cuttlefish.
      Overall usage decreases by 112 KB.
Change-Id: I0419aa9378570936f15a97a9ab814b035dee4c06