Update mbed-coap to version 4.5.0

[anttiylitokola]

Description

Fix error: IIOTCLT-2769 - mbed-coap: extra response received after registration

Added own flag to enable blockwise support, without setting default blockwise
payload size. This allows to receive blockwise messages while still sending
without blockwise.

Fix CoAP request blockwise response handling
When request is sent, response can have blockwise option set. All requests must
be stored to the linked list.

Pull request type

[x] Fix
[ ] Refactor
[ ] New target
[ ] Feature
[ ] Breaking change

[anttiylitokola]

@yogpan01, please review

[yogpan01]

Looks ok, approved. This commit is required also by Thread for their inter-interoperability testing.
FYI @terhei @artokin.

[0xc0170]

/morph build

[mbed-ci]

Build : SUCCESS

Build number : 2448
Build artifacts/logs : http://mbed-os.s3-website-eu-west-1.amazonaws.com/?prefix=builds/7320/

Triggering tests

/morph test
/morph uvisor-test
/morph export-build
/morph mbed2-build

[mbed-ci]

Test : SUCCESS

Build number : 2227
Test logs :http://mbed-os-logs.s3-website-us-west-1.amazonaws.com/?prefix=logs/7320/2227

[mbed-ci]

Exporter Build : FAILURE

Build number : 2079
Build artifacts/logs : http://mbed-os.s3-website-eu-west-1.amazonaws.com/?prefix=builds/exporter/7320/

[cmonr]

Relaunching since this appears to have been a Jenkins Node failure.

/morph export-build

[cmonr]

/morph export-build

[mbed-ci]

Exporter Build : SUCCESS

Build number : 2083
Build artifacts/logs : http://mbed-os.s3-website-eu-west-1.amazonaws.com/?prefix=builds/exporter/7320/

[adbridge]

@anttiylitokola Out of curiosity if this is just a fix release why has the coap minor release version gone up rather than just the patch version? Technically we should not be taking minor releases of any other component into our patch releases. We need to get more consistent across modules with semantic versioning.