Testsuite: improve tests for block/bytecode options

Improve the model that is used to test all combinations of algorithms with
block and bytecode options, by ensuring that it includes the 8 possible types of blocks:
– Solve {forward, backward, two boundaries} {simple, complete}
– Evaluate {forward, backward}

All the “Solve” blocks are also included in both linear and nonlinear forms
(since the codepaths are typically different depending on the linearity of
the block).

Note that there is no such thing as a nonlinear “Evaluate” block, since the
endogenous variables of the block always enter linearly (on the LHS).

Also:
- use perfect_foresight_{setup,solver} instead of simul (and disable automatic homotopy)
- add a shock on e_R (though this is not strictly needed since the
  corresponding block already inherits the shock from another ancestor block)
- remove the block for observables, there is already another block of type
  “Evaluate forward”