meta-bletchley: detect-gpio-present: sled present managerment service

A service to monitor the presence status of sleds and perform
corresponding actions when sleds are inserted or removed.

This patch require phosphor-gpio-monitor-presence enabled and gpio-keys
defined in kernel dts file, the LORE link as below.
* https://lore.kernel.org/all/20220613095150.21917-4-potin.lai.pt@gmail.com/

Signed-off-by: Potin Lai <potin.lai@quantatw.com>
Change-Id: Id43c7c5c40ccad904db3e6d55870b154a68626ca
diff --git a/meta-facebook/meta-bletchley/recipes-bletchley/detect-gpio-present/files/detect-sled-present@.service b/meta-facebook/meta-bletchley/recipes-bletchley/detect-gpio-present/files/detect-sled-present@.service
new file mode 100644
index 0000000..d9cfe86
--- /dev/null
+++ b/meta-facebook/meta-bletchley/recipes-bletchley/detect-gpio-present/files/detect-sled-present@.service
@@ -0,0 +1,13 @@
+[Unit]
+Description=SLED%i Present Manager
+After=phosphor-gpio-presence@presence-sled%i.service
+Wants=phosphor-gpio-presence@presence-sled%i.service
+After=mapper-wait@-xyz-openbmc_project-inventory-system-chassis-presence-presence_sled%i.service
+Wants=mapper-wait@-xyz-openbmc_project-inventory-system-chassis-presence-presence_sled%i.service
+
+[Service]
+ExecStart=/usr/bin/detect-sled-present %i
+Type=simple
+
+[Install]
+WantedBy=multi-user.target