Update systemd unit files

- Add instance name to template units
- Change service type to `idle` for frpc
- Check config file existence before starting

conf/systemd/frpc.service

@@ -1,9 +1,10 @@
 [Unit]
 Description=Frp Client Service
 After=network.target
+StartLimitIntervalSec=3
 
 [Service]
-Type=simple
+Type=idle
 User=nobody
 Restart=on-failure
 RestartSec=5s

conf/systemd/frpc@.service

@@ -1,12 +1,14 @@
 [Unit]
-Description=Frp Client Service
+Description=Frp Client Service (%i)
 After=network.target
+StartLimitIntervalSec=3
 
 [Service]
 Type=idle
 User=nobody
 Restart=on-failure
 RestartSec=5s
+ExecStartPre=/bin/test -s /etc/frp/%i.ini
 ExecStart=/usr/bin/frpc -c /etc/frp/%i.ini
 ExecReload=/usr/bin/frpc reload -c /etc/frp/%i.ini
 

conf/systemd/frps.service

@@ -1,12 +1,14 @@
 [Unit]
 Description=Frp Server Service
 After=network.target
+StartLimitIntervalSec=3
 
 [Service]
 Type=simple
 User=nobody
 Restart=on-failure
 RestartSec=5s
+ExecStartPre=/bin/test -s /etc/frp/frps.ini
 ExecStart=/usr/bin/frps -c /etc/frp/frps.ini
 
 [Install]

conf/systemd/frps@.service

@@ -1,12 +1,14 @@
 [Unit]
-Description=Frp Server Service
+Description=Frp Server Service (%i)
 After=network.target
+StartLimitIntervalSec=3
 
 [Service]
 Type=simple
 User=nobody
 Restart=on-failure
 RestartSec=5s
+ExecStartPre=/bin/test -s /etc/frp/%i.ini
 ExecStart=/usr/bin/frps -c /etc/frp/%i.ini
 
 [Install]