Add blog post about long term statistic API changes (#1531)

Co-authored-by: Franck Nijhof <[email protected]>

Author: emontnemery

blog/2022-11-16-statistics_refactoring.md

@@ -0,0 +1,29 @@
+---
+author: Erik Montnemery
+authorURL: https://github.com/emontnemery
+title: "Changes to long term statistics APIs"
+---
+
+Some changes have been made to the long-term statistics-related APIs to reduce response size and database load.
+
+The changes are implemented in [this PR](https://github.com/home-assistant/core/pull/82131).
+
+This affects authors of code calling the following WS APIs:
+ - `recorder/statistics_during_period`
+   - A new optional parameter `types` has been added, which allows providing a list of statistics characteristics to include in the response. Possible values are: `"last_reset"`, `"max"`, `"mean"`, `"min"`, `"state"`, `"sum"`
+   - Timestamps `start`, `end` and `last_reset` are now an integer number of ms since the UNIX epoch instead of ISO-formatted strings. The new format means the timestamps can be passed directly to js `Date()` constructor.
+   - The `statistic_id` is no longer repeated for each list item in the returned map. This was not used because the return type is a map, keyed by `statistic_id`.
+
+This affects authors of code calling the following Python APIs:
+- `homeassistant.recorder.statistics.get_last_short_term_statistics`
+  - A new parameter `types` has been added, which allows providing a set of statistics characteristics to include in the response. Possible values are: `"last_reset"`, `"max"`, `"mean"`, `"min"`, `"state"`, `"sum"`
+  - Timestamps `start`, `end` and `last_reset` are now an `datetime` objects instead of ISO-formatted strings.
+  - The `statistic_id` is no longer repeated for each list item in the returned map. This was not used because the return type is a map, keyed by `statistic_id`.
+- `homeassistant.recorder.statistics.get_latest_short_term_statistics`
+  - A new parameter `types` has been added, which allows providing a set of statistics characteristics to include in the response. Possible values are: `"last_reset"`, `"max"`, `"mean"`, `"min"`, `"state"`, `"sum"`
+  - Timestamps `start`, `end` and `last_reset` are now an `datetime` objects instead of ISO-formatted strings.
+  - The `statistic_id` is no longer repeated for each list item in the returned map. This was not used because the return type is a map, keyed by `statistic_id`.
+- `homeassistant.recorder.statistics.statistics_during_period`
+  - A new parameter `types` has been added, which allows providing a set of statistics characteristics to include in the response. Possible values are: `"last_reset"`, `"max"`, `"mean"`, `"min"`, `"state"`, `"sum"`
+  - Timestamps `start`, `end` and `last_reset` are now an `datetime` objects instead of ISO-formatted strings.
+  - The `statistic_id` is no longer repeated for each list item in the returned map. This was not used because the return type is a map, keyed by `statistic_id`.