Don't make EEPROM size assumptions with dynamic keymaps. (#16054)

* Don't make EEPROM size assumptions with dynamic keymaps.

* Add support for checking against emulated flash, error out if someone attempts to build a board without specifying EEPROM size.

* Reorder defines so that MCU is considered last.

* Refactor EEPROM definitions for simplicity.

* Fix max sizing of kabedon/kabedon980.

* Fix max sizing of mechlovin/olly/jf.

* Fix unit tests.

* Review comments, add messages with values during build failures.

platforms/chibios/eeprom_teensy.h

@@ -0,0 +1,22 @@
+// Copyright 2022 Nick Brassel (@tzarc)
+// SPDX-License-Identifier: GPL-2.0-or-later
+#pragma once
+
+#if defined(K20x)
+/* Teensy 3.0, 3.1, 3.2; mchck; infinity keyboard */
+// The EEPROM is really RAM with a hardware-based backup system to
+// flash memory.  Selecting a smaller size EEPROM allows more wear
+// leveling, for higher write endurance.  If you edit this file,
+// set this to the smallest size your application can use.  Also,
+// due to Freescale's implementation, writing 16 or 32 bit words
+// (aligned to 2 or 4 byte boundaries) has twice the endurance
+// compared to writing 8 bit bytes.
+//
+#    ifndef EEPROM_SIZE
+#        define EEPROM_SIZE 32
+#    endif
+#elif defined(KL2x) /* Teensy LC (emulated) */
+#    define EEPROM_SIZE 128
+#else
+#    error Unsupported Teensy EEPROM.
+#endif