Add exchange context implementation

[andy31415]

Problem

Previous WML baseline port included the CHIPExchangeMgr header and cpp file, however apparently the cpp for the exchange context is separated.

Summary of Changes

Added ExchangeContext.cpp from weave-core.

[github-actions]

Size increase report for "nrf-example-build"

File	Section	File	VM

Full report output

BLOAT REPORT

Files found only in the build output:
    report.csv

Comparing ./master_artifact/chip-nrf52840-lock-example.out and ./pull_artifact/chip-nrf52840-lock-example.out:

sections,vmsize,filesize

[github-actions]

Size increase report for "linux-example-build"

File	Section	File	VM

Full report output

BLOAT REPORT

Files found only in the build output:
    report.csv

Comparing ./master_artifact/chip-standalone-demo.out and ./pull_artifact/chip-standalone-demo.out:

sections,vmsize,filesize

[woody-apple]

Looks great, a few questions/comments - and things to maybe update / sync up on.

[woody-apple]

I thought secure channel didn't want message ID reuse? @RyanTheOptimist @balducci-apple

[andy31415]

This is a straight copy from weave, no attempts at updating. I think we should update in separate PRs (lots of cleanup needed in general).

I expect the entire security model needs to be plugged out and replaced with SCTT.

[yufengwangca]

@woody-apple

This is just the strait copy of the missing parts in WML, these files are not the final version and not get linked at this moment.

We are working on integrating the existing session management logic to this baseline in separate PRs. Here is the open items list for this effort:
https://github.com/project-chip/connectedhomeip/labels/cleanup_wml_baseline

[robszewczyk]

Yes, this should be dropped. This is a bit of a vestigial code that we're not pulling into CHIP (this was aimed at a self regulating group communication pattern that implemented a trickle algorithm, and we're happy to pull that out). To that end, we should pull out:

• The flag as identified here
• ResendMessage implementation (in ExchangeContext only)
• any if statements guarded with references to Trickle
• TeardownTrickleRetransmit
• StartTimerT
• StartTimerTau
• TimerT
• TimerTau
• HandleTrickleMessage
• SetupTrickleRetransmit

[github-actions]

Size increase report for "gn_nrf-example-build"

File	Section	File	VM

Full report output

BLOAT REPORT

Files found only in the build output:
    report.csv

[github-actions]

Size increase report for "gn_linux-example-build"

File	Section	File	VM

Full report output

BLOAT REPORT

Files found only in the build output:
    report.csv

[github-actions]

Size increase report for "nrfconnect-example-build"

File	Section	File	VM

Full report output

BLOAT REPORT

Files found only in the build output:
    report.csv

Comparing ./master_artifact/chip-nrf52840-lock-example.elf and ./pull_artifact/chip-nrf52840-lock-example.elf:

sections,vmsize,filesize

[github-actions]

Size increase report for "esp32-example-build"

File	Section	File	VM

Full report output

BLOAT REPORT

Files found only in the build output:
    report.csv

Comparing ./master_artifact/chip-wifi-echo.elf and ./pull_artifact/chip-wifi-echo.elf:

sections,vmsize,filesize