Support explicit estimates and smoothed enrolment values

[Brian Lewis]

For Kiribati; interpolated values have been calculated where data is missing, rather than use the traditional ‘estimate’ = best historic values.

Such estimates' are flagged by setting enOrigin:

SMOOTHING: the value is used, is counted as an estimate for purposes of % estimates, other pupil table data (Repeaters disability) still use traditional historic estimate.

EXPLICIT : the value is used, is counted as an estimate for purposes of % estimates, other pupil table data (Repeaters disability) is taken from the survey year. ie EXPLCLIT is treated exactly as a normal ‘actual’ value, expect it is counted as an Estimate.

[Brian Lewis]

Since a stat digest is being published using such smooth values, this modification is necessary to allow KEMIS portal and uIS survey to align with the Stats Digest,

[Brian Lewis]

feat(reporting): support SMOOTHING in enrolments

Resolves #1249

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