[RFC] Rename lldb-vscode to lldb-dap

@JDevlieghere , after giving this a second thought, wouldn’t it be better to rename the binary to lldb-dap-server? dap is the protocol, and this binary is a server implementation for that protocol. This becomes more visible when writing python tests for the dap server, where there’s clearly a client and server. To give an specific example, there’s a variable in your current PR that is called self.dap, and that would look much cleaner as self.dap_server or self.server.
What do you think?