This change updates the log format to use the vscode log format instead
of the custom log format, by replacing the `OutputChannel` with a
`LogOutputChannel` and using the `debug`, `info`, `warn`, and `error`
methods on it. This has the following benefits:
- Each log level now has its own color and the timestamp is in a more
standard format
- Inspect output (e.g. the log of the config object) is now colored
- Error stack traces are now shown in the output
- The log level is now controlled on the output tab by clicking the gear
icon and selecting "Debug" or by passing the `--log` parameter to
vscode. The `trace.extension` setting has been marked as deprecated.
Everything now happens in main.ts, in the bootstrap family of
functions. The current flow is:
* check everything only on extension installation.
* if the user is on nightly channel, try to download the nightly
extension and reload.
* when we install nightly extension, we persist its release id, so
that we can check if the current release is different.
* if server binary was not downloaded by the current version of the
extension, redownload it (we persist the version of ext that
downloaded the server).
There are too many of them, and they no longer match the set of crates
we have.
This really should be handled in a different way, by having out
"rust-analyzer: Run" generate the appropriate lldb config on the fly.
