scripted-diff: s/WITH_MULTIPROCESS/ENABLE_IPC/ in cmake

Rename WITH_MULTIPROCESS to ENABLE_IPC, because ENABLE_IPC is a more accurate
name for the feature. It controls whether the src/ipc/ directory is built and
whether IPC features like -ipcbind, -ipcconnect, and -ipcfd are available. It
does NOT currently enable multiprocess features which are implemented in #10102
building on top of the IPC features. It will also no longer (as of the next
commit), control whether a find_package call is made so the "WITH_" prefix is
also inappropriate.

-BEGIN VERIFY SCRIPT-
git grep -l WITH_MULTIPROCESS | xargs sed -i s/WITH_MULTIPROCESS/ENABLE_IPC/g
-END VERIFY SCRIPT-

doc/design/libraries.md

@@ -8,7 +8,7 @@
 | *libbitcoin_crypto*      | Hardware-optimized functions for data encryption, hashing, message authentication, and key derivation. |
 | *libbitcoin_kernel*      | Consensus engine and support library used for validation by *libbitcoin_node*. |
 | *libbitcoinqt*           | GUI functionality used by *bitcoin-qt* and *bitcoin-gui* executables. |
-| *libbitcoin_ipc*         | IPC functionality used by *bitcoin-node*, *bitcoin-wallet*, *bitcoin-gui* executables to communicate when [`-DWITH_MULTIPROCESS=ON`](multiprocess.md) is used. |
+| *libbitcoin_ipc*         | IPC functionality used by *bitcoin-node*, *bitcoin-wallet*, *bitcoin-gui* executables to communicate when [`-DENABLE_IPC=ON`](multiprocess.md) is used. |
 | *libbitcoin_node*        | P2P and RPC server functionality used by *bitcoind* and *bitcoin-qt* executables. |
 | *libbitcoin_util*        | Home for common functionality shared by different executables and libraries. Similar to *libbitcoin_common*, but lower-level (see [Dependencies](#dependencies)). |
 | *libbitcoin_wallet*      | Wallet functionality used by *bitcoind* and *bitcoin-wallet* executables. |