[DPE-3689, DPE-4179] Expose read-write and read-only endpoints when related to data-integrator + TLS support (#119)

## Issue
1. We are currently not reacting to `external-node-connectivity` that
may be sent to mysql-router via data-interfaces when related with
data-integrator
2. We are not able to relate with the TLS operators
3. We broke upgrades
(#130) when we
implemented reconcile pattern for COS

## Solution
1. Support `external-node-connectivity` by binding to address `0.0.0.0`
when related to data-integrator. Else, only expose router through a unix
socket
2. Add capability to relate to TLS operators
3. Refactor to fix upgrades -- remaining integration test will be added
in a follow up PR

## Testing
Added integration tests for TLS + COS, TLS, and TLS + Data Integrator

## todo
~~Change the `charmed-mysql` snap version to the official `8.0/edge`
version instead of a branch build~~

Author: shayancanonical

.github/workflows/ci.yaml

@@ -116,6 +116,9 @@ jobs:
           - juju-snap-channel: "2.9/stable"
             agent-version: "2.9.45"
             libjuju-version:  "2.9.44.1"
+        exclude:
+          - groups: {path_to_test_file: tests/integration/test_data_integrator.py}
+            ubuntu-versions: {series: focal}
     name: ${{ matrix.juju-snap-channel }} - (GH hosted) ${{ matrix.groups.job_name }} | ${{ matrix.ubuntu-versions.series }}
     needs:
       - lint

actions.yaml

@@ -12,3 +12,12 @@ force-upgrade:
     Use to
     - force incompatible upgrade and/or
     - continue upgrade if 1+ upgraded units have non-active status
+set-tls-private-key:
+  description:
+    Set the private key, which will be used for certificate signing requests (CSR). Run
+    for each unit separately.
+  params:
+    internal-key:
+      type: string
+      description: The content of private key for internal communications with
+        clients. Content will be auto-generated if this option is not specified.

charmcraft.yaml

@@ -27,6 +27,12 @@ parts:
           echo 'ERROR: Use "tox run -e build" instead of calling "charmcraft pack" directly' >&2
           exit 1
       fi
+    build-packages:
+      - libffi-dev
+      - libssl-dev
+      - pkg-config
+      - rustc
+      - cargo
     charm-entrypoint: src/machine_charm.py
     prime:
       - charm_version