Add the ability to update user passwords with ansible (when using the matrix-postgres container).

roles/matrix-synapse/templates/synapse/usr-local-bin/matrix-synapse-generate-password-hash.j2

@@ -0,0 +1,31 @@
+#!/usr/bin/env expect
+
+# Read the password string
+set pass [lindex $argv 0]
+
+# Check if password was provided
+if { $pass == "" }  {
+  puts "Usage: $argv0 <password>"
+  exit 1
+}
+
+# Disable output
+log_user 0
+
+# Execute password hashing script
+spawn docker exec -it matrix-synapse /usr/local/bin/hash_password -c /data/homeserver.yaml
+expect "Password: "
+send "$pass\r"
+expect "Confirm password: "
+send "$pass\r"
+expect "%"
+
+# Save the hash output to a variable
+set output $expect_out(buffer)
+
+# Trim the whitespace
+regexp {\S+} $output passwordHash
+
+# Output the password hash
+puts -nonewline stdout $passwordHash
+close stdout