feat: use exponential backoff algorithm when polling actions (#524)

##### SUMMARY

Replace the constant poll interval of 1 second, with a truncated
exponential back off algorithm with jitter.

Below is a suite of poll interval (in seconds) generated by the new
algorithm:
```
1.49
2.14
5.46
6.51
6.57
5.57
5.98
7.13
6.59
7.10
5.54
5.03
6.56
5.96
6.72
7.21
7.05
5.31
5.60
6.33
6.82
5.42
6.08
6.60
TOTAL: 140.77
```

tests/unit/module_utils/test_client.py

@@ -0,0 +1,14 @@
+from __future__ import annotations
+
+from ansible_collections.hetzner.hcloud.plugins.module_utils.client import (
+    exponential_backoff_poll_interval,
+)
+
+
+def test_exponential_backoff_poll_interval():
+    poll_interval = exponential_backoff_poll_interval(base=1.0, multiplier=2, cap=5.0, jitter=0.0)
+    poll_max_retries = 25
+
+    results = [poll_interval(i) for i in range(poll_max_retries)]
+    assert sum(results) == 117.0
+    assert results[:6] == [1.0, 2.0, 4.0, 5.0, 5.0, 5.0]