Improve interface of lens.find method

[karelklima]

The interface should enable user to do more powerful queries, order results, and find specific resources more easily.

Prisma could be a good inspiration in what to accomplish:

const results = await prisma.post.findMany({
  skip: 200,
  take: 20,
  where: {
    email: {
      contains: 'Prisma',
    },
  },
  orderBy: {
    title: 'desc',
  },
})

[karelklima]

As for the operators = they should correspond to sparql boolean FILTER functions, e.g. regex, contains, lang, is.

Alternatively, there could be a filter definition that would translate directly to SPARQL, e.g.:

{
  where: {
    someNumber: {
      filter: "? > 10",
    },
  },
}

[karelklima]

Partially resolved by #65.

[karelklima]

Ordering is out of scope and not really aligned with the Linked Data concepts supported by LDkit. Closing.