Set minimum brightness for neopixel light

**Describe the problem you have/What new integration you would like**

I would like to limit minimum brightness for neopixel (like WS2812 and etc), especially if the gamma correction is higher than 3 to avoid led strip off if I set the low brightness. I need higher gamma correction for better colors of my WS2812 LED strip (like 4.2) but then I can't set brightness under 30% because the leds are going off even the light is on.

**Please describe your use case for this integration and alternatives you've tried:**

Add the `min_power` or `min_brightness` for neopixel light which will set the minimum brightness of light like the `min_power` for PWM output for lights using pwms (like RGB, RGBW, CWWW and etc). Also add max bvrightness will be good too,.

**Additional context**

Start by locating the existing neopixel light integration and the PWM light handling for min_power. Compare how minimum and maximum brightness are defined, then verify that the requested minimum-brightness behavior works with high gamma correction and does not turn the WS2812 strip off at low settings.

Written by the indexing model from the issue text.