#### ⚠️ targets #10051
## Summary of the Pull Request
This PR does one big, primary thing. It removes all the constructors from any TerminalConnections, and changes them to use an `Initialize` method that accepts a `ValueSet` of properties.
Why?
For the upcoming window/content process work, we'll need the content process to be able to initialize the connection _in the content process_. However, the window process will be the one that knows what type of connection to make. Enter `ConnectionInformation`. This class will let us specify the class name of the type we want to create, and a set of settings to use when initializing that connection.
**IMPORTANT**: As a part of this, the constructor for a connection must have 0 arguments. `RoActivateInstance` lets you just conjure a WinRT type just by class name, but that class must have a 0 arg ctor. Hence the need for `Initialize`, to actually pass the settings.
We're using a `ValueSet` here because it's basically a json blob, with more steps. In the future, when extension authors want to have custom connections, we can always deserialize the json into a `ValueSet`, pass it to their connection's `Initialize`, and let then get what they need out of it.
## References
* Tear-out: #1256
* Megathread: #5000
* Project: https://github.com/microsoft/terminal/projects/5
## PR Checklist
* [x] Closes https://github.com/microsoft/terminal/projects/5#card-50760298
* [x] I work here
* [n/a] Tests added/passed
* [n/a] Requires documentation to be updated
## Detailed Description of the Pull Request / Additional comments
`ConnectionInformation` was included as a part of this PR, to demonstrate how this will eventually be used. `ConnectionInformation` is not _currently_ used.
## Validation Steps Performed
It still builds and runs.
If a class has a constructor which can be called with a single argument,
then this constructor becomes conversion constructor because such a
constructor allows conversion of the single argument to the class being
constructed. To ensure these constructors are passed the argument of its
type, I labeled them explicit.
In some header files, there were constructors that took a value that
could involve implicit conversions, so I added explicit to ensure that
does not happen.
This commit adds a debugging feature that can be activated by holding
down Left Alt _and_ Right Alt when a new tab is being created, if you
have the global setting "debugFeatures" set to true. That global setting
will default to true in DEBUG builds.
That debugging feature takes the form of a split pane that shows the raw
VT sequences being written to and received from the connection.
When those buttons are held down, every connection that's created as
part of a new tab is wrapped and split into _two_ connections: one to
capture input (and stand in for the main connection) and one to capture
output (and be displayed off to the side)
Closes#3206
