Add mutual TLS authentication support

[bobbyiliev]

What type of PR is this? (check all applicable)

• ♻️ Refactor
• ✨ Feature
• 🐛 Bug Fix
• 👷 Optimization
• 📝 Documentation Update
• 🚩 Other

Description

Adding support for mutual TLS authentication.

The user needs to set the following env vars:

# For Kafka SSL Authentication:
SSL_CA_LOCATION=
SSL_CERT_LOCATION=
SSL_KEY_LOCATION=

We will have the following precedence:

• If SASL env details are set, we will default to that
• Next in order will be TLS details
• Finally, if none are set we will default to no auth, eg. locally running Kafka

Related Tickets & Documents

Closes #69

Added to documentation?

• 📜 readme
• 🙅 no documentation needed

[optional] What gif best describes this PR or how it makes you feel?

[sjwiesman]

+1 assuming you've used