Refactor code for restoring files via shell commands

Presently, restore_command uses a different code path than
archive_cleanup_command and recovery_end_command.  These code paths
are similar and can be easily combined, as long as it is possible to
identify if a command should:
- Issue a FATAL on signal.
- Exit immediately on SIGTERM.

While on it, this removes src/common/archive.c and its associated
header.  Since the introduction of c96de2c, BuildRestoreCommand() has
become a simple wrapper of replace_percent_placeholders() able to call
make_native_path().  This simplifies shell_restore.c as long as
RestoreArchivedFile() includes a call to make_native_path().

Author: Nathan Bossart
Reviewed-by: Andres Freund, Michael Paquier
Discussion: https://postgr.es/m/20221227192449.GA3672473@nathanxps13

src/fe_utils/archive.c

@@ -19,8 +19,8 @@
 #include <sys/stat.h>
 
 #include "access/xlog_internal.h"
-#include "common/archive.h"
 #include "common/logging.h"
+#include "common/percentrepl.h"
 #include "fe_utils/archive.h"
 
 
@@ -41,13 +41,18 @@ RestoreArchivedFile(const char *path, const char *xlogfname,
 {
 	char		xlogpath[MAXPGPATH];
 	char	   *xlogRestoreCmd;
+	char	   *nativePath;
 	int			rc;
 	struct stat stat_buf;
 
 	snprintf(xlogpath, MAXPGPATH, "%s/" XLOGDIR "/%s", path, xlogfname);
 
-	xlogRestoreCmd = BuildRestoreCommand(restoreCommand, xlogpath,
-										 xlogfname, NULL);
+	nativePath = pstrdup(xlogpath);
+	make_native_path(nativePath);
+	xlogRestoreCmd = replace_percent_placeholders(restoreCommand,
+												  "restore_command", "fp",
+												  xlogfname, nativePath);
+	pfree(nativePath);
 
 	/*
 	 * Execute restore_command, which should copy the missing file from