Implicit chemisty implementation

[moprak-nrel]

Add a routine that can handle implicit chemistry time advancement, along with a "Strang" splitting time stepping between the flow and chemistry solves.

[hsitaram]

Can you add an example inputs file for blockCatalyst1d with the implicit integrator?
Also, anything like SUNDIALS_LIB_DIR that I need to set in the GNUMakefile, can you add that in the blockCatalyst1d as a commented line

[moprak-nrel]

Added the implicit options in the blockCatalyst1d directory.

The implicit integration was verified for this case with k=5*1e5 instead of k=5, at this rate the explicit chemistry does not work, but the implicit version works as expected.

[moprak-nrel]

Verification of the implicit solve: x direction was run with new implicit solve, y direction used new explicit RK3, z direction is the current explicit implementation. This is for the k=5 case.

verification.pdf