Use m5gfx::delay for internal hardware waits

[ainyan03]

Problem

M5.delay() is a plain vTaskDelay(msec / portTICK_PERIOD_MS), so it
truncates to the tick period and can only undershoot. With the ESP-IDF
default tick rate of 100 Hz (10 ms tick), M5.delay(1) through
M5.delay(9) perform no delay at all — just a yield. The Arduino core's
1000 Hz tick hides this, but ESP-IDF builds use the shorter waits as
written:

• the I2C init retry backoff (M5Unified.cpp) becomes a busy retry loop,
• the ES8388 soft-ramp transition wait (M5Unified.cpp) waits for nothing,
• the BQ27220 sub-command wait of 10 ms can shrink to zero.

m5gfx::delay() waits coarsely with vTaskDelay and completes short
remainders with a microsecond busy-wait, so it guarantees at least the
requested time regardless of the tick configuration.

Fix

Internal waits that exist for hardware timing reasons now use
m5gfx::delay(), matching what Power_Class.cpp already does everywhere.
M5.delay() itself is unchanged and remains the sketch-facing convenience
API.

BQ27220_Class.cpp referenced the global M5 object only for these
delays, so its include narrows from M5Unified.h to M5GFX.h.

[Copilot]

Pull request overview

This PR updates internal hardware timing waits to use m5gfx::delay() so short delays don’t collapse to a zero-time yield under coarse FreeRTOS tick configurations (notably ESP-IDF defaults), while keeping M5.delay() unchanged as the sketch-facing API.

Changes:

• Replaced internal M5.delay(…) calls used for hardware timing with m5gfx::delay(…) in M5Unified.cpp.
• Switched BQ27220_Class.cpp from M5Unified.h to M5GFX.h after removing its last dependency on the global M5 object.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
src/utility/power/BQ27220_Class.cpp	Uses m5gfx::delay() for BQ27220 timing waits and narrows includes to M5GFX.h.
src/M5Unified.cpp	Uses m5gfx::delay() for I2C retry backoff and ES8388 soft-ramp transition wait to guarantee minimum delay time.

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