Considering the number of reports of "defterm isn't working (mysteriously)", I figured more logging current hurt. I also added a wprp profile for the defterm logging as well, which should capture conhost side things as well.
From an elevated conhost:
```
wpr -start path\to\Terminal.wprp!Defterm.Verbose
wpr -stop %USERPROFILE%\defterm-trace.etl
```
* [x] I work here
* [x] relevant to: #10594, #11529, #11524.
Adds a check before every UIA function call to ensure the terminal (specifically the buffer) is initialized before doing work. Both the `ScreenInfoUiaProvider` and the `UiaTextRange` are now covered.
## References
Closes#11135#10971 & #11042
## Detailed Description of the Pull Request / Additional comments
Originally, I tried applying this heuristic to all the `RuntimeClassInitialize` on `UiaTextRangeBase` with the philosophy of "a range pointing to an invalid buffer is invalid itself", but that caused a regression on [MSFT 33353327](https://microsoft.visualstudio.com/OS/_workitems/edit/33353327).
`IUiaData` also has `GetTextBuffer()` return a `TextBuffer&`, which cannot be checked for nullness. Instead, I decided to add a function to `IUiaData` that checks if we have a valid state. Since this is shared with Conhost and Conhost doesn't have this issue, I simply make that function say that it's always in a valid state.
## Validation Steps Performed
- [X] Narrator can detect newly created terminals
- [X] (On Windows Server 2022) Windows Terminal does not hang on launch
Set keyword flags on all events so those sharing a provider with
telemetry do not fire unless tracing is enabled
## PR Checklist
* [x] Closes#10093
* [x] I work here
* [x] Tests passed
* [x] Documentation added in `til.h` about how keywords work and at the
only other site of keywords we define in the Host project tracing
files.
## Detailed Description of the Pull Request / Additional comments
I initially thought that we would need to split providers here to
accomplish this... but @DHowett helped me realize that might be a lot of
additional metadata and bloat binary size. So with help from a friend
from fundamentals, I realized that we could use Keywords to
differentiate here. We can no longer define 0 keywords as that
represents an any/all scenario. Every `TraceLoggingWrite` event now
needs a keyword. When our events have a keyword, they're not included in
any trace. Additionally, when we have an explicit keyword to check that
is different from the ones used for the telemetry pipeline, we can
ensure that we only do "hard work" to generate debug trace data when an
"ALL" type listener like TraceView or Windows Performance Recorder with
our profiles is listening to these providers for ALL keyworded events.
## Validation Steps Performed
- [x] - Built with full release build config to confirm performance is
worse than dev builds BECAUSE of the telemetry event collector camping
our provider and triggering full trace event generation on shared
providers.
- [x] - Built with full release build config to enable statistics
collection and validated trace event collection is excluded and trace
event short-circuits work with this change.
- [x] - Checked that TraceView still sees both telemetry and tracing
events
- [x] - Checked that WPR with our .wprp profile sees both telemetry and
tracing events
