Use to_underlying instead of manually writing it out or static asserts.

[bzbarsky-apple]

Cleans up some code now that we don't have to choose between
cumbersome template bits with decltype and std::underlying_type_t and
cassting to a fixed type which might be wrong.

Problem

Code is uglier than it has to be.

Change overview

Use our shiny new to_underlying to make it less ugly.

Testing

Should be no behavior changes. Normal CI tests for that.

[github-actions]

Size increase report for "esp32-example-build" from 0e19e0d

File	Section	File	VM
chip-all-clusters-app.elf	.flash.text	-24	-24
chip-lock-app.elf	.flash.text	64	64

Full report output

BLOAT REPORT

Files found only in the build output:
    report.csv

Comparing ./master_artifact/chip-all-clusters-app.elf and ./pull_artifact/chip-all-clusters-app.elf:

sections,vmsize,filesize
.debug_info,0,3122
.debug_str,0,1745
.debug_line,0,311
.xt.prop._ZN4chip6System5Mutex6UnlockEv,0,108
.debug_abbrev,0,107
.xt.lit._ZN4chip11DeviceLayer8Internal35GenericPlatformManagerImpl_FreeRTOSINS0_19PlatformManagerImplEE14_LockChipStackEv,0,48
.xt.lit._ZN4chip11DeviceLayer8Internal35GenericPlatformManagerImpl_FreeRTOSINS0_19PlatformManagerImplEE15_StartChipTimerEj,0,48
.xt.lit._ZN4chip11DeviceLayer8Internal35GenericPlatformManagerImpl_FreeRTOSINS0_19PlatformManagerImplEE16_UnlockChipStackEv,0,48
[Unmapped],0,24
.xt.prop._ZN4chip11DeviceLayer8Internal35GenericPlatformManagerImpl_FreeRTOSINS0_19PlatformManagerImplEE14_LockChipStackEv,0,12
.xt.prop._ZN4chip11DeviceLayer8Internal35GenericPlatformManagerImpl_FreeRTOSINS0_19PlatformManagerImplEE15_StartChipTimerEj,0,12
.xt.prop._ZN4chip11DeviceLayer8Internal35GenericPlatformManagerImpl_FreeRTOSINS0_19PlatformManagerImplEE16_UnlockChipStackEv,0,12
.debug_loc,0,-5
.flash.text,-24,-24
.xt.prop._ZN4chip11DeviceLayer8Internal26GenericPlatformManagerImplINS0_19PlatformManagerImplEE14_InitChipStackEv,0,-40
.xt.lit._ZN4chip11DeviceLayer8Internal35GenericPlatformManagerImpl_FreeRTOSINS0_19PlatformManagerImplEE10_PostEventEPKNS0_15ChipDeviceEventE,0,-80
.xt.lit._ZN4chip6System5Mutex6UnlockEv,0,-128

Comparing ./master_artifact/chip-lock-app.elf and ./pull_artifact/chip-lock-app.elf:

sections,vmsize,filesize
.debug_info,0,2122
.debug_str,0,889
.debug_line,0,231
.flash.text,64,64
.debug_abbrev,0,43
.debug_loc,0,11
[Unmapped],0,-64

Comparing ./master_artifact/chip-temperature-measurement-app.elf and ./pull_artifact/chip-temperature-measurement-app.elf:

sections,vmsize,filesize
.debug_info,0,2226
.debug_str,0,889
.debug_line,0,247
.debug_abbrev,0,65
.debug_loc,0,5

Comparing ./master_artifact/chip-shell.elf and ./pull_artifact/chip-shell.elf:

sections,vmsize,filesize
.debug_info,0,657
.debug_str,0,543
.debug_line,0,97
.debug_abbrev,0,18
.debug_loc,0,5

Comparing ./master_artifact/chip-pigweed-app.elf and ./pull_artifact/chip-pigweed-app.elf:

sections,vmsize,filesize

Comparing ./master_artifact/chip-persistent-storage.elf and ./pull_artifact/chip-persistent-storage.elf:

sections,vmsize,filesize

[bzbarsky-apple]

@jmartinez-silabs @LuDuda @andy31415 @mspang @jepenven-silabs @Damian-Nordic please take a look?