Copter: Transition to Brake prior to executing Failsafe action

#### Feature Request details
Not an issue, but an observation. Some part my fault, some part the mechanics of how the system operates. When flying Sport mode, I was in and out of some obstacles. The Battery critical failsafe was set to RTL, which is fine, except it occurred at the precise moment I was straffing around said obstacles. Because the RTL action occurred with excessive lateral momentum, the drone maintained that momentum without agressively stopping movement. That momentum carried it right into the object. Without question I could have either not had that as my failsafe, or switch back to a controllable mode (which is what I almost always do anyways), but the former was an afterthought, and the latter was not possible given how quickly the action occurred.

My suggestion is the addition of "Brake Mode" until movement is halted, and then progress to the failsafe mode. This would potentially (hopefully) be a parameterized option, because i'm sure there are those that wouldn't want this to occur.

Additionally, it would be an option for each of the main failsafe functions (battery, low_throttle, etc)

#### Platform
[ ] All
[ ] AntennaTracker
[X ] Copter
[ ] Plane
[ ] Rover
[ ] Submarine

#### Airframe type
Quadcopter

Start with the requested Copter behavior in the issue body: transition to Brake before executing battery, low-throttle, and other failsafe actions. Determine how a parameterized choice would apply across those actions, and consider the obstacle-avoidance and momentum scenarios described. Done means the selected failsafe can halt movement before continuing, while users can opt out.

Written by the indexing model from the issue text.