Add support for time entities

[jesserockz]

What does this implement/fix?

Adds support for time entities. This is pretty much the same as date entities with the obvious difference.

Related PRs:

• Implement datetime time entity aioesphomeapi#850
• ESPHome: Add Time Entity support home-assistant/core#113852
• Bump aioesphomeapi to 23.2.0 home-assistant/core#113854

Types of changes

• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Other

Related issue or feature (if applicable): fixes

Pull request in esphome-docs with documentation (if applicable): esphome/esphome-docs#3748

Test Environment

• ESP32
• ESP32 IDF
• ESP8266
• RP2040
• BK72xx
• RTL87xx

Example entry for config.yaml:

# Example config.yaml

datetime:
  - platform: template
    type: time
    optimistic: true
    name: Time
    id: my_time
    restore_value: true
    on_value:
      - logger.log:
          format: "The time is now: %02d:%02d:%02d"
          args:
            - x.hour
            - x.minute
            - x.second

Checklist:

• The code change is tested and works locally.
• Tests have been added to verify that the new code works (under tests/ folder).

If user exposed functionality or configuration variables are added/changed:

• Documentation added/updated in esphome-docs.

[probot-esphome]

Hey there @RFDarter, mind taking a look at this pull request as it has been labeled with an integration (datetime) you are listed as a code owner for? Thanks!
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[probot-esphome]

Hey there @OttoWinter, mind taking a look at this pull request as it has been labeled with an integration (api) you are listed as a code owner for? Thanks!
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[gabest11]

Can you take a look at #6424 ? I see you also used strptime. This function eliminates 1M devices from ESPHome because it uses std::regex... Smart plugs, etc. With OTA there is max 500k space and even a barebone config is nearly that big.

[gabest11]

Then you need to call DateTimeBase::strptime instead, Which does not exists until this is merged. Can't you move it there in your PR? And this can be cancelled then.

[gabest11]

Ignore my last comment, putting ifdefs in time.h. strptime will stay there.

[jesserockz]

Converting to draft as I need to add the on_time trigger

[jesserockz]

Depends on #6468

[probot-esphome]

Hey there @RFDarter, mind taking a look at this pull request as it has been labeled with an integration (datetime) you are listed as a code owner for? Thanks!
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