feat(frontends/lean/parser): display elaborator error messages

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
fix(frontends/lean/pp): missing comma when printing contexts

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
fix(frontends/lean/parser): option propagation

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
fix(tests/lean): adjust error messages in the expected output

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
fix(elaborator): max constraints

elaborator was not handling max constraints where one of the arguments was a Bool. Example:
      ctx |- max(Bool, Type) == ?M

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>