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.

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.