* introduced a new communication command CMD_FLASHMEM_PAGES64K to get the number of 64k pages
* "the last page" is a special, holding the dicts and some other stuff, relocated to there
* raised timeout when wiping a mem page (W25Q16 looks a bit slower than W25X20BV)
* loop all pages in Flash_WipeMemory()
* Add `.ramfunc` section to bootrom loader script
* exclude spiffs functionality from flashmem.h/flashmem.c
(allows bootrom to use flashmem)
* hide unused tick.h / flashmem.h functions from bootrom
(not technically necessary; see comments)
* bootrom: add source files, include path, and defines when
`PLATFORM_DEFS` defines `WITH_FLASH`
* Define `AS_BOOTROM` to indicate code is building for bootrom
