rather than setting the heap size statically, micropython allocates
the biggest contiguous chunk possible, but in no event more than half the
total internal sram. On esp32 this gives 123728 bytes of `gc.mem_free`
in the repl.
Also, change error handling so that the esp-idf error number
is shown in the traceback in the case of an error.
This allows scanning & connecting to work. I didn't try requests yet.
esp32 places the psram start at SOC_EXTRAM_DATA_LOW and it can extend
up to SOC_EXTRAM_DATA_SIZE. This is different than esp32-s2 and later,
which place the end at EXTRAM_DATA_HIGH and the limitation of
SOC_EXTRAM_DATA_SIZE was not previously identified as important.
Additionally, the esp32 has a reserved area within himem which was
not being accounted for.
With this change, the Feather ESP32 V2 feather can be used via thonny,
and the other "quick memory corruption tests" I was performing
also all succeed instead of failing.
Before this change, the incorrect address being used for spiram was
0x3fa00000..0x3fc00000 (2MiB). Now, it's 0x3f800000..0x3f9c0000 (1.75MiB)
due to the reserved area and the changed start address.
This is intended to be a no-effect change for other espressif chips besides
original esp32.
addr2line can show information about how functions were inlined,
including function names
Typical new output:
```
0x400dec57: mp_obj_get_type at /home/jepler/src/circuitpython/ports/espressif/../../py/obj.c:68
(inlined by) mp_obj_print_helper at /home/jepler/src/circuitpython/ports/espressif/../../py/obj.c:133
(inlined by) mp_obj_print_helper at /home/jepler/src/circuitpython/ports/espressif/../../py/obj.c:114
0x400e1a25: fun_builtin_1_call at /home/jepler/src/circuitpython/ports/espressif/../../py/objfun.c:75
0x400dd016: mp_call_function_n_kw at /home/jepler/src/circuitpython/ports/espressif/../../py/runtime.c:665
0x400eac99: mp_execute_bytecode at /home/jepler/src/circuitpython/ports/espressif/../../py/vm.c:936
0x400e1ae9: fun_bc_call at /home/jepler/src/circuitpython/ports/espressif/../../py/objfun.c:297 (discriminator 4)
0x400dd016: mp_call_function_n_kw at /home/jepler/src/circuitpython/ports/espressif/../../py/runtime.c:665
0x400dd03a: mp_call_function_0 at /home/jepler/src/circuitpython/ports/espressif/../../py/runtime.c:638
0x40117c03: parse_compile_execute at /home/jepler/src/circuitpython/ports/espressif/../../shared/runtime/pyexec.c:146
0x4011800d: pyexec_friendly_repl at /home/jepler/src/circuitpython/ports/espressif/../../shared/runtime/pyexec.c:734
0x400eeded: run_repl at /home/jepler/src/circuitpython/ports/espressif/../../main.c:823
(inlined by) main at /home/jepler/src/circuitpython/ports/espressif/../../main.c:922
0x400ef5e3: app_main at /home/jepler/src/circuitpython/ports/espressif/supervisor/port.c:410
0x401bb461: main_task at /home/jepler/src/circuitpython/ports/espressif/build-adafruit_feather_esp32_v2/esp-idf/../../esp-idf/components/freertos/port/port_common.c:141
```
