Improve find nearest stitchable keypoints set

[Benvii]

Find nearest stitchable keypoints (or CP) should use these rules :

• find nearest stitchable CP in 30 meter area if found return it
• find nearest lot by id which as stitchable CP, return these cp if found
• throw an error and set a flag in CP database indicating that we didn't found any nearest stitchable CP

As panorama are gloabaly stitched by order, if one of the first images isn't stitchable we might not found stitchable images before this one. So we will set a flag in the database to be able to retry it when keypoints sets are generated.

This will involve a database migration to add this flag, the name should be nearestCpFound, and default value null.

[Benvii]

• Database flag issu referenced here : https://github.com/OpenPathView/OPV_DBRest/issues/23
• Treament issu referenced here : https://github.com/OpenPathView/OPV_Dags/issues/1