Add support for Application Set Time

[mablem8]

• Add a description of Application Set Time to DOCUMENTATION.md
• Add Application Set Time to c-implementation/tab.c with an external handler
• Add a handler implementation of Application Set Time to cdh.c
• Add a handler implementation of Application Set Time to com.c
• Add an implementation of Application Set Time to python-implementation/tab.py
• Add testing of Application Set Time in python-examples/tx/tx_example.py
• Test support for Application Set Time with c-examples/cdh-monolithic and python-examples/tx

[ChadTaylor17]

• Add a description of Application Set Time to DOCUMENTATION.md
• Add Application Set Time to c-implementation/tab.c with an external handler
• Add a handler implementation of Application Set Time to cdh.c
• Add a handler implementation of Application Set Time to com.c
• Add an implementation of Application Set Time to python-implementation/tab.py
• Add testing of Application Set Time in python-examples/tx/tx_example.py
• Test support for Application Set Time with c-examples/cdh-monolithic and python-examples/tx

Tests:
txcmd: app_set_time hw_id:0x1234 msg_id:0x000c src:gnd dst:cdh sec:731089187 ns:946978000
reply: common_ack hw_id:0x1234 msg_id:0x000c src:cdh dst:gnd

Commit: c35549e

[mablem8]

There are some issues preventing a merge of commit c35549e.

Issues with compilation

Because this commit adds external handlers for setting and getting the time in the TAB C implementation, and because these handlers have only been added to the CDH example and not the COM example, the COM example no longer compiles (i.e., a regression). When leaving a portion of the code unimplemented, be sure to add empty handlers with hard-coded success values so that the programs still compile.

Issues with attribution

Since this commit adds code written by Shize Che during the summer and fall of 2021, be sure to add his name to the contributors lists at the top of the appropriate files.

Issues with workflow

Because the proposed commit also includes a proposed fix for another issue, the proposed fix to this issue cannot be tested independently from the code aimed at the other issue. If, for example, the fix for this issue passes but the fix for the other issue fails, then the commit would be prevented from being merged despite containing a working fix.

Issues with comment formatting

When posting test results, use three ` characters to indicate the start of an output block, and use three of that same character to end the output block.

[ChadTaylor17]

Commits for app set time: 509eabf and 92daa56