Enable debug mode in with_sentry_client

[loewenheim]

There is a comment in with_sentry_client about debug mode:

sentry-cli/src/utils/event.rs

Lines 84 to 85 in 554f4fc

	// TODO: do we want to eventually set `debug` based on the CLI log-level?
	// debug: true,

Since the help message of send-envelope (which uses with_sentry_client) says

Check debug output for transmission errors by passing --log-level=debug or setting SENTRY_LOG_LEVEL=debug.

we should probably go through with this.

[elramen]

This applies to send-event also

[elramen]

Instead of using with_sentry_client, we could probably use EnvelopesApi which will be added to sentry-cli