Add basic arbitrary waveform generation support for PS3000A series

[MatFi]

This PR adds support for arbitrary waveform generation for PS3000A series oscilloscopes. The main changes include:

1. Added new global variables to track PS3000A-specific AWG states:

PS3000A_EXTRA_OPERATIONS g_awgPS3000AOperation = PS3000A_ES_OFF;
PS3000A_WAVE_TYPE g_awgPS3000AWaveType = PS3000A_SINE;

2. WaveformType structure has been created to standardise the handling of waveform types in different Pico models and to facilitate the support of new models:

struct WaveformType {
    PICO_WAVE_TYPE type6000;
    PS3000A_WAVE_TYPE type3000;
    PS3000A_EXTRA_OPERATIONS op3000;
};

3. Added square wave generation functionality with configurable duty cycle, as this is not supported by the SigGenBuiltIn function:

void GenerateSquareWave(int16_t* &waveform, size_t bufferSize, double dutyCycle, int16_t amplitude);

Testing:

• Tested wave generation with various settings / duty cycles
• Verified compatibility with existing PS6000A functionality. I don't have access to one and need support here, Although I don't expect any issues.
• Tested AWG start/stop behavior on PS3000A hardware

Missing

• Support for custom arbitrary waveforms (until I figured out how to define waveforms with ngscopeclient)
• Proper AWG buffer management

Note:

• See 3000 series: support function generator
  Let me know if you would like me to adjust any part of this PR description or if you have any suggestions in general.