kleaf: Expose CcInfo provider from ddk_headers rule

Update `ddk_headers` rule in `kleaf/impl/ddk/ddk_headers.bzl` to
construct and export a `CcInfo` provider transitively from dependencies.

Add helper function `ddk_headers_cc_info_transitively()` which gathers
include paths and compilation context headers from `hdrs` and
`textual_hdrs` targets that provide `CcInfo` (such as `kernel_headers`
or dependent `ddk_headers`), allowing downstream DDK targets to
transitively propagate C/C++ compilation contexts.

Bug: 517401745
Change-Id: I47e8529177a419be21591f868202ab3bf2830ea2
Signed-off-by: Lucas Wei <lucaswei@google.com>