cmake: Move internal binaries from bin/ to libexec/

This change moves binaries that are not typically invoked directly by users
from the `bin/` directory to the `libexec/` directory in CMake installs and
binary releases. The goal is to simplify the contents of `bin/` for end users
while still making all binaries available when needed. After this change, the
binaries remaining in `bin/` are:

- bitcoin
- bitcoin-cli
- bitcoind
- bitcoin-qt
- bitcoin-tx
- bitcoin-util
- bitcoin-wallet

And the binaries that are moved to `libexec/` are:

- bench_bitcoin
- bitcoin-chainstate(*)
- bitcoin-gui(***)
- bitcoin-node(***)
- test_bitcoin(**)
- test_bitcoin-qt

(*) bitcoin-chainstate was previously missing an install rule and was actually
not installed even when it was enabled.

(**) test_bitcoin is the only libexec/ binary that is currently included in
bitcoin binary releases. The others are only installed when building from
source with relevant cmake options enabled.

(***) bitcoin-node and bitcoin-gui are not currently built by default or
included in binary releases but both of these changes are planned and
implemented in #31802

contrib/macdeploy/detached-sig-create.sh

@@ -44,7 +44,7 @@ ${SIGNAPPLE} apply "${UNSIGNED_BUNDLE}" "${OUTROOT}/${BUNDLE_ROOT}/${BUNDLE_NAME
 ${SIGNAPPLE} notarize --detach "${OUTROOT}/${BUNDLE_ROOT}" --passphrase "${api_key_pass}" "$2" "$3" "${UNSIGNED_BUNDLE}"
 
 # Sign each binary
-find . -maxdepth 3 -wholename "*/bin/*" -type f -exec realpath --relative-to=. {} \; | while read -r bin
+find . -maxdepth 3 \( -wholename "*/bin/*" -o -wholename "*/libexec/*" \) -type f -exec realpath --relative-to=. {} \; | while read -r bin
 do
     bin_dir=$(dirname "${bin}")
     bin_name=$(basename "${bin}")