Add non-blocking write function for USBCDC

[omdathetkan]

Description

For certain applications it is desirable to do a non-blocking write when sending larger blocks of data over USBSerial. I am proposing to add a second function to USBCDC to support this. Does anyone have suggestions on how to implement this in the API?

bool USBSerial::writeBlock(uint8_t * buf, uint16_t size) {
    if(size > MAX_PACKET_SIZE_EPBULK) {
        return false;
    }
    if(!send(buf, size)) {
        return false;
    }
    return true;
}

There could be an optional argument bool blocking=true, or a second function writeBlockNB, or make it always non-blocking?

Pull request type

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

[0xc0170]

@jorisa There's feature usb branch that might address this (@c1728p9 can confirm and review this). This should be the branch https://github.com/ARMmbed/mbed-os/tree/feature-hal-spec-usb-device

[0xc0170]

/morph build

[mbed-ci]

Build : SUCCESS

Build number : 2316
Build artifacts/logs : http://mbed-os.s3-website-eu-west-1.amazonaws.com/?prefix=builds/7090/

Triggering tests

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

[mbed-ci]

Exporter Build : SUCCESS

Build number : 1939
Build artifacts/logs : http://mbed-os.s3-website-eu-west-1.amazonaws.com/?prefix=builds/exporter/7090/

[cmonr]

/morph mbed2-build

[mbed-ci]

Test : FAILURE

Build number : 2095
Test logs :http://mbed-os-logs.s3-website-us-west-1.amazonaws.com/?prefix=logs/7090/2095

[cmonr]

Updated comment since this PR feels like it's more of a feature addition than a fix.

Rerunning test since failures appear to be focused around a device that had to be restarted today.
/morph test

[cmonr]

/morph mbed2-build

[cmonr]

We're looking into some CI issues at the moment. The test will be restarted when the dust has settled.

[mbed-ci]

Test : FAILURE

Build number : 2101
Test logs :http://mbed-os-logs.s3-website-us-west-1.amazonaws.com/?prefix=logs/7090/2101

[cmonr]

Re-queued since failure was due to a newly discovered htrun bug.

/morph test

[mbed-ci]

Test : SUCCESS

Build number : 2115
Test logs :http://mbed-os-logs.s3-website-us-west-1.amazonaws.com/?prefix=logs/7090/2115