[thread] Allow to specify dataset timestamp

[Damian-Nordic]

Problem

4008 removed setting Thread Dataset Active Timestamp to make sure that a provisioned device collects missing Thread settings from a border router. The problem is it may be too restrictive, since it's now impossible to start the device as a Thread leader as the leader role requires that the timestamp be initialized.

Summary of Changes

• Extend the DeviceNetworkInfo structure to allow to specify the Thread Dataset Active Timestamp.
• Slightly optimize the structure size.

[github-actions]

Size increase report for "esp32-example-build" from 4bbe313

File	Section	File	VM
chip-all-clusters-app.elf	.flash.text	-4	-4

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,0,70
.debug_str,0,23
.xt.prop._ZTVN4chip11DeviceLayer37DeviceNetworkProvisioningDelegateImplE,0,1
.debug_loc,0,-2
.flash.text,-4,-4

[github-actions]

Size increase report for "nrfconnect-example-build" from 4bbe313

File	Section	File	VM
chip-lighting.elf	shell_root_cmds_sections	8	8
chip-lighting.elf	text	8	8
chip-lock.elf	shell_root_cmds_sections	8	8
chip-lock.elf	text	8	8

Full report output

BLOAT REPORT

Files found only in the build output:
    report.csv

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

sections,vmsize,filesize
.debug_info,0,88
.debug_loc,0,25
.debug_str,0,23
shell_root_cmds_sections,8,8
text,8,8
.debug_line,0,-8
.debug_ranges,0,-8

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

sections,vmsize,filesize
.debug_info,0,88
.debug_loc,0,25
.debug_str,0,23
shell_root_cmds_sections,8,8
text,8,8
.debug_line,0,-8
.debug_ranges,0,-8

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

sections,vmsize,filesize
.debug_str,0,23
.debug_info,0,16
.debug_loc,0,13
.debug_line,0,12

[rwalker-apple]

@saurabhst @hawk248 @jelderton @BroderickCarlin ?