Handle normalizations and regularizations more flexibly

[ndiamant]

What
Model normalizers and regularizers placed automatically in correct order

Why
Normalizers and regularizers are currently placed in fixed positions, which prevents the use of some useful techniques. For example, L2 regularization is impossible because right now because regularization layer comes after the activation instead of the layer.

How
Dictionary mapping regularization enum or string to position in block.

Acceptance Criteria

• Dictionary mapping regularization enum or string to position in block
• New regularizations + normalizations properly used (especially L2, layer norm)
• Command line allows multiple regularizations
• Command line fails early on nonexistent regularizations and normalizations