floss: Fix "unused manifest key" warning

hcidoc toml:
  The correct name is "crate-type" (no trailing s). This means that we
  were not specifying it before. The default value is ["lib"] where
  "lib" is an alias to "rlib" for now - It could change in the future
  rustc version. Anyway this patch explicitly sets it to "rlib".

gd/rust tomls:
  The "build" key should be in the [package] section. "build.rs" is the
  default value so this shall have no behavior changes.

Bug: 332634317
Tag: #floss
Test: mmm packages/modules/Bluetooth
Test: floss/build/build-in-container.py
Test: emerge-brya floss
Test: emerge floss_tools
Flag: EXEMPT, Floss-only changes
Change-Id: I9d8ecd4b708f3f3fcd1d0966edc552b669f854a8