[Simulator] An alternative simple quadratic DP for simulator

[xumingkuan]

Changes to the simulator:

• Adds an alternative DP Schedule::compute_kernel_schedule_simple running in O(n^2) where n is the number of gates; get_schedules() now calls this DP by default
• kernel.h now does #include "quartz/simulator/kernel_cost.h"; adds helper functionsKernel::add_gate()andKernel::cost()` to update a kernel and get its cost conveniently
• Changes the directory for running test_simulation from quartz/ to quartz/build
• Fix some comments and some warnings about signed-to-unsigned comparisons
• Benchmark: qft, 33 qubits, 28 local qubits

Before (complicated DP):

2 stages.
Kernel info: 13 kernels (10 fusion, 3 shared-memory), cost = 268.5, local qubits 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32
Kernel info: 4 kernels (4 fusion, 0 shared-memory), cost = 25.4, local qubits 5 6 7 8 9 10 11 12 13 28 29 30 31 32 19 20 21 22 23 24 25 26 27 0 1 2 3 4
6 seconds.

After https://github.com/quantum-compiler/quartz/commit/22a6d42ddb09b4a0b19d2eee7719286f8f28def6 (simple DP without considering the fact that shared-memory kernels only need the non-insular qubits to be active):

2 stages.
Kernel info: 68 kernels (14 fusion, 54 shared-memory), cost = 582.4, local qubits 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32
Kernel info: 4 kernels (4 fusion, 0 shared-memory), cost = 25.4, local qubits 5 6 7 8 9 10 11 12 13 28 29 30 31 32 19 20 21 22 23 24 25 26 27 0 1 2 3 4
0 seconds.

After this PR:

2 stages.
Kernel info: 11 kernels (8 fusion, 3 shared-memory), cost = 271.5, local qubits 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32
Kernel info: 4 kernels (4 fusion, 0 shared-memory), cost = 25.4, local qubits 5 6 7 8 9 10 11 12 13 28 29 30 31 32 19 20 21 22 23 24 25 26 27 0 1 2 3 4
0 seconds.

Global changes:

• Changed the default build type from Release to Debug for faster development and easier debugging
• Minor bug fixes:
  • In QASMParser, handle \r correctly in Windows environments
  • In QASMParser, fix the wrong location of an assertion