Add couple more sensors for SDM meters

**Describe the problem you have/What new integration you would like**

**Please describe your use case for this integration and alternatives you've tried:**

**Additional context**

Hi,

In new 1.19.1 you have added SDM meters as sensor will it be possible to add also other sensors for SDM630 such as:
#define SDM630_IMPORT1 0x015a //kWh
#define SDM630_IMPORT2 0x015c //kWh
#define SDM630_IMPORT3 0x015e //kWh
#define SDM630_EXPORT1 0x0160 //kWh
#define SDM630_EXPORT2 0x0162 //kWh
#define SDM630_EXPORT3 0x0164 //kWh
#define SDM630_TOTAL_ENERGY1 0x0166 //kWh
#define SDM630_TOTAL_ENERGY2 0x0168 //kWh
#define SDM630_TOTAL_ENERGY3 0x016a //kWh
#define SDM630_POWERTOTAL 0x0034 //W
#define SDM630_CURRENTSUM 0x0030 //A

I know you made it universal and put sensors which is similar to all of the meters but it will be good to separate them for each SDM meter so user can define which SDM meter he has. Some of them is usefull and it's beter to read them directly from meter than make some automation.

No repository file, test, or entry point is named. Start by locating the existing SDM meter sensor implementation and its register definitions, then verify how meter-specific selection works; done means the requested SDM630 readings are available as sensors without breaking existing meter support.

Written by the indexing model from the issue text.