Dronecan set param function sending incorrect value for integer strings

#### Issue details
Large strings that can equate as an integer number cause the dronecan set parameter function to send in scientific notation.

#### Version
1.3.74 checked on master and it's still present.

#### Platform
[ X] All
[ ] AntennaTracker
[ ] Copter
[ ] Plane
[ ] Rover
[ ] Sub

#### Airframe type
Any
#### Hardware type
Cube orange / bluemark remote ID module. Hardware type doesn't effect the issue.

#### Logs
No logs but in the function here https://github.com/ArduPilot/MissionPlanner/blob/master/ExtLibs/DroneCAN/DroneCAN.cs#L2024

When a string is greater than 12 digits all numeric (probably less than this number. This is the length of the number I was using.) the object converts the string into to scientific notation.

Start at ExtLibs/DroneCAN/DroneCAN.cs around line 2024 and inspect how the set-parameter function converts numeric strings before sending them. Reproduce the issue with a numeric string longer than 12 digits, then verify that the transmitted value remains the original integer string rather than scientific notation.

Written by the indexing model from the issue text.