bpf: suppress false-positive clang-tidy/clangd diagnostics under src/bpf

bpf: suppress false-positive clang-tidy/clangd diagnostics under src/bpf

clang-tidy's misc-use-internal-linkage fires on BPF map declarations
(they have the SEC(".maps") attribute and must retain external linkage
so bpftool gen skeleton can resolve them as ELF symbols), and its
misc-include-cleaner flags errno.h as unused even where a /* IWYU
pragma: keep */ is present. clangd's own unused-includes analysis
emits the equivalent diagnostic independently of clang-tidy.

Add src/bpf/.clang-tidy and src/bpf/.clangd that inherit the parent
configs and scope these suppressions to BPF sources only.