meta-digi: add awsiotsdk-c configuration class

This commit adds an awsiotsdk-c class to encapsulate all AWS IoT device SDK
configurations.

In general, the variables are the macros that users can configure in their
'aws_iot_config.h' file.

See for example, the header file for the 'shadow_sample' at GitHub:
https://github.com/aws/aws-iot-device-sdk-embedded-C/blob/master/samples/linux/shadow_sample/aws_iot_config.h

https://jira.digi.com/browse/DEL-4101

Signed-off-by: Tatiana Leon <tatiana.leon@digi.com>

meta-digi-dey/classes/awsiotsdk-c.bbclass

@@ -0,0 +1,65 @@
+# Adds AWS IoT device SDK for embedded C configuration
+#
+
+# Customer specific MQTT HOST
+AWS_IOT_MQTT_HOST ?= ""
+
+# Default port for MQTT/S
+AWS_IOT_MQTT_PORT ?= "8883"
+
+# Thing Name of the Shadow the device is associated with
+AWS_IOT_MY_THING_NAME ?= "AWS-IoT-C-SDK"
+
+# Root CA file name
+AWS_IOT_ROOT_CA_FILENAME ?= "rootCA.crt"
+
+# Device signed certificate file name
+AWS_IOT_CERTIFICATE_FILENAME ?= "cert.pem"
+
+# Device private key filename
+AWS_IOT_PRIVATE_KEY_FILENAME ?= "privkey.pem"
+
+# MQTT PubSub
+
+# Any time a message is sent out through the MQTT layer. The message is copied
+# into this buffer anytime a publish is done.
+# This will also be used in the case of Thing Shadow
+AWS_IOT_MQTT_TX_BUF_LEN ?= "512"
+
+# Any message that comes into the device should be less than this buffer size.
+# If a received message is bigger than this buffer size the message will be
+# dropped
+AWS_IOT_MQTT_RX_BUF_LEN ?= "512"
+
+# Maximum number of topic filters the MQTT client can handle at any given time.
+# This should be increased appropriately when using Thing Shadow
+AWS_IOT_MQTT_NUM_SUBSCRIBE_HANDLERS ?= "5"
+
+# Thing Shadow specific configs
+
+# At any given time we will wait for this many responses.
+# This will correlate to the rate at which the shadow actions are requested
+MAX_ACKS_TO_COMEIN_AT_ANY_GIVEN_TIME ?= "10"
+
+# We could perform shadow action on any thing Name and this is maximum Thing
+# Names we can act on at any given time
+MAX_THINGNAME_HANDLED_AT_ANY_GIVEN_TIME ?= "10"
+
+# These are the max tokens that is expected to be in the Shadow JSON document.
+# It includes the metadata that gets published
+MAX_JSON_TOKEN_EXPECTED ?= "120"
+
+# The Thing Name should not be bigger than this value. Modify this if the Thing
+# Name needs to be bigger
+MAX_SIZE_OF_THING_NAME ?= "20"
+
+# Auto Reconnect specific config
+
+# Minimum time before the First reconnect attempt is made as part of the
+# exponential back-off algorithm (milliseconds)
+AWS_IOT_MQTT_MIN_RECONNECT_WAIT_INTERVAL ?= "1000"
+
+# Maximum time interval after which exponential back-off will stop attempting
+# to reconnect (milliseconds)
+AWS_IOT_MQTT_MAX_RECONNECT_WAIT_INTERVAL ?= "128000"
+