Make "getId" type function naming consistent.

There is a lot of mixing of getId and getID. Arguments could be made for either, but we should be consistent.

Examples:

Here: https://github.com/openframeworks/openFrameworks/issues/3780

GLuint ofBufferObject::getId() const;
GLuint VertexAttribute::getId() const;
GLuint IndexAttributegetId() const;
const GLuint& ofBaseGLRenderer::getCurrentFramebufferId() const; and sub-classes.
int ofLight::getLightID() const;
ofSoundDevice::deviceID
int ofBaseSoundStream::getDeviceID() const = 0;
unsigned int ofSoundBuffer::getDeviceID() const;
void ofBaseVideoGrabber::setDeviceID(int _deviceID); and sub-classes.
int ofThread::getThreadId() const;
ofQTKitGrabber::getDeviceID();
ofQTKitGrabber::getVideoDeviceID();
ofQTKitGrabber::getAudioDeviceID();
int ofRtAudioSoundStream::getDeviceID() const
int ofSerialDeviceInfo::getDeviceID();

    GLuint getVaoId() const;
    GLuint getVertId() const;
    GLuint getColorId() const;
    GLuint getNormalId() const;
    GLuint getTexCoordId() const;
    GLuint getIndexId() const;

    /// returns OpenGL memory object id for GL buffer holding attribute data
    GLuint  getAttributeId(int AttrPos_) const;

Start by reviewing issue 3780 and the listed declarations, including ofBufferObject::getId(), ofLight::getLightID(), and the getDeviceID variants. Search the C++ sources for getId and getID usages to determine the scope and affected callers. Done means the chosen naming convention is applied consistently without leaving the listed variants unresolved.