ExprNumericOps is not typesafe with PostgreSQL

[bishabosha]

The signature of Numeric ops e.g. that RHS adapts to LHS type is wrong:
e.g. using

class ExprNumericOps[T: Numeric](v: Expr[T]) {
  def *[V: Numeric](x: Expr[V]): Expr[T] // note that rhs is Expr[V] that gets co-erced to Expr[T]
}

incorrect version:
(type checks but runtime error: org.postgresql.util.PSQLException: Bad value for type int : 16750695023.881126)

val tenLanguagesSpokenByLargestPopulation: Seq[(String, Int)] = db.run(
  City.select
    .join(CountryLanguage.select)((city, lang) => city.cc === lang.cc)
    .map((city, lang) => (lang.lang, lang.pct, city.pop))
    .groupBy((lang, pct, pop) => lang)(agg => agg.sumBy((_, pct, pop) => pop * pct))
    .sortBy((lang, pc) => pc).desc
    .take(10)
)

correct version (swap multiplication):

-val tenLanguagesSpokenByLargestPopulation: Seq[(String, Int)] = db.run(
+val tenLanguagesSpokenByLargestPopulation: Seq[(String, Double)] = db.run(
   City.select
     .join(CountryLanguage.select)((city, lang) => city.cc === lang.cc)
     .map((city, lang) => (lang.lang, lang.pct, city.pop))
-    .groupBy((lang, pct, pop) => lang)(agg => agg.sumBy((_, pct, pop) => pop * pct))
+    .groupBy((lang, pct, pop) => lang)(agg => agg.sumBy((_, pct, pop) => pct * pop)) // swap to `pct * pop`
     .sortBy((lang, pc) => pc).desc
     .take(10)
 )

Either there could be some hardcoded overloads for various float/integral combinations, or there chould be some typelevel gymnastics to return the "greedy" type so order does not matter, or there could be implicit evidence that prevents incorrect combinations of numeric types, and suggest to swap the arguments

[npcrusde]

seems related to #89