auto compress updated html

[ryancdotorg]

Description:

Currently, Tasmota developers need to remember to manually run the script to compress HTML with unishox, due to this being somewhat slow.

This PR adds checks to the process to automatically skip compression for uncompressed files which have not changed, and enables the process by default.

Checklist:

• The pull request is done against the latest development branch
• Only relevant files were touched
• Only one feature/fix was added per PR and the code change compiles without warnings
• The code change is tested and works with Tasmota core ESP8266 V.2.7.8
• The code change is tested and works with Tasmota core ESP32 V.3.1.0.241206
• I accept the CLA.

NOTE: The code change must pass CI tests. Your PR cannot be merged unless tests pass

[Jason2866]

@s-hadinger @arendst regarding the Platformio implementation it LGTM
unishox is your part ;-)

[s-hadinger]

This looks good to me. Thanks Ryan