tmf: Add a method to verify if analysis is ready at timestamp

tmf: Add a method to verify if analysis is ready at timestamp

First step to resolve bug 488757. This new method will return whether an
analysis is ready to be queried at a given timestamp.

Change-Id: I2a1f597d503fe74664df95d0bb5c4c16952b6376
Signed-off-by: Geneviève Bastien <gbastien+lttng@versatic.net>
Reviewed-on: https://git.eclipse.org/r/69753
Reviewed-by: Hudson CI
Reviewed-by: Bernd Hufmann <bernd.hufmann@ericsson.com>
Tested-by: Bernd Hufmann <bernd.hufmann@ericsson.com>