[Inclined 1D/2D elements] Part 2: HeatConduction process

Following up MR !3632 (merged), this MR enables to use inclined 1D/2D elements in HeatConduction process. The major changes are:

1. vector output of the heat flux,
2. use inclined 1D/2D elements. A new benchmark is added to test computation with inclined elements as shown in the following figure:

where the orientation of the heat flux is exactly on the domain plane as expected.

This MR fixes #3253 (closed).

1. Feature description was added to the changelog
2. Tests covering your feature were added? The reference files of some benchmark due to the change of heat flux output.
3. Any new feature or behavior change was documented?