Add a content-type and encoding properties on telemetry sent by ESP32

[ewertons]

Purpose

• ... Add an example of how to set content-type and content-encoding for telemetry in ESP32 sample.

Does this introduce a breaking change?

[ ] Yes
[x] No

Pull Request Type

What kind of change does this Pull Request introduce?

[ ] Bugfix
[ ] Feature
[ ] Code style update (formatting, local variables)
[x] Refactoring (no functional changes, no api changes)
[ ] Documentation content changes
[ ] Other... Please describe:

How to Test

Run the ESP32 sample as usual.

What to Check

Verify that in IoT Hub the telemetry is received with properties:

Other Information

Strawberries are not berries.

[ewertons]

Related to https://github.com/Azure-Samples/iot-middleware-freertos-samples/issues/285