core: add support for setting CPUAffinity= to special "numa" value

systemd will automatically derive CPU affinity mask from NUMA node
mask.

Fixes #13248

src/core/execute.h

@@ -182,6 +182,7 @@ struct ExecContext {
 
         CPUSet cpu_set;
         NUMAPolicy numa_policy;
+        bool cpu_affinity_from_numa;
 
         ExecInput std_input;
         ExecOutput std_output;
@@ -406,6 +407,8 @@ void exec_runtime_vacuum(Manager *m);
 
 void exec_params_clear(ExecParameters *p);
 
+bool exec_context_get_cpu_affinity_from_numa(const ExecContext *c);
+
 const char* exec_output_to_string(ExecOutput i) _const_;
 ExecOutput exec_output_from_string(const char *s) _pure_;