Implement UI scaling and more (#501)

**New Features**
 * Runtime font accessors and new symbol fonts for text, launcher, statusbar, and shared icons.
 * Added font height base setting to device.properties
 * Text fonts now have 3 sizes: small, default, large

**Improvements**
 * Renamed `UiScale` to `UiDensity`
 * Statusbar, toolbar and many UI components now compute heights and spacing from fonts/density.
 * SSD1306 initialization sequence refined for more stable startup.
 * Multiple image assets replaced by symbol-font rendering.
 * Many layout improvements related to density, font scaling and icon scaling
 * Updated folder name capitalization for newer style

Platforms/platform-esp32/private/tactility/drivers/esp32_gpio_helpers.h

@@ -0,0 +1,32 @@
+#pragma once
+
+#include <tactility/drivers/gpio_descriptor.h>
+
+#include <driver/gpio.h>
+
+/**
+ * Releases the given pin descriptor and sets the pointer value to NULL.
+ * If the descriptor pointer is null, do nothing.
+ */
+void release_pin(GpioDescriptor** gpio_descriptor);
+
+/**
+ * Acquires the pin descriptor for the given pin spec.
+ * If the pin spec is invalid, the pointer is set to null.
+ * @return true if the pin was acquired successfully
+ */
+bool acquire_pin_or_set_null(const GpioPinSpec& pin_spec, GpioDescriptor** gpio_descriptor);
+
+/**
+ * Safely acquire the native pin value.
+ * Set to GPIO_NUM_NC if the descriptor is null.
+ * @param[in] descriptor Pin descriptor to acquire
+ * @return Native pin number
+ */
+gpio_num_t get_native_pin(GpioDescriptor* descriptor);
+
+/**
+ * Returns true if the given pin is inverted.
+ * @param[in] descriptor Pin descriptor to check, nullable
+ */
+bool is_pin_inverted(GpioDescriptor* descriptor);