Install + package remsim-apitool as separate sub-package

As the script depends on python3, let's put it into a new
osmo-remsim-apitool package.

As we're installing the tool system-wide, rename it from
remsim-apitool.py to osmo-remsim-apitool.

Closes: OS#5612
Change-Id: I11d779f66833b5294ffeb422ce6b2a705719a899
diff --git a/debian/osmo-remsim-apitool.install b/debian/osmo-remsim-apitool.install
new file mode 100644
index 0000000..fd47f34
--- /dev/null
+++ b/debian/osmo-remsim-apitool.install
@@ -0,0 +1 @@
+usr/bin/osmo-remsim-apitool