ENH: Support FIND and COUNT queries

Summary

See https://gitlab.indiscale.com/caosdb/customers/lfpb/management/-/issues/399. Introduces FIND and Count queries.

Focus

Most changes are in transaction.h and transaction.cpp.

Test Environment

Unit and integration tests with server in f-grpc-f-query

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• All automated tests pass
• Reference related Issues
• [ ] Up-to-date CHANGELOG.md
• Annotations in code (Gitlab comments)
  • Intent of new code
  • Problems with old code
  • Why this implementation?

Check List for the Reviewer

• I understand the intent of this MR
• All automated tests pass
• [ ] Up-to-date CHANGELOG.md
• The test environment setup works and the intended behavior is reproducible in the test environment
• In-code documentation and comments are up-to-date.
• Check: Are there specifications? Are they satisfied?

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include/caosdb/transaction.h

@@ -246,17 +246,6 @@ private:
   std::unique_ptr<Entity> entity;
 };
 
-// TODO(fspreck) One possibility for count-queries: Transaction gets a
-// GetQueryCount function that returns exactly this. In case of a
-// single FIND Query this will be equivalent to the Size of the
-// ResultSet, but it may be different in case of Query + RetrieveById,
-// and in case of COUNT queries which have an empty ResultSet. We have
-// to think about how to extend this to transactions with more than
-// one query in the future. My suggestion is to treat a transaction
-// with more than one query as the union of the query results in which
-// case the query count would return the cumulative number of
-// results. This would even allow the combination of FIND, FIND
-// unique, and COUNT, albeit a little strangely.
 /**
  * @brief Create a transaction via `CaosDBConnection.createTransaction()`
  */
@@ -375,7 +364,7 @@ public:
    * this transaction. In all other cases, the return value will be
    * -1.
    */
-  [[nodiscard]] inline auto GetCountResult() const -> int {
+  [[nodiscard]] inline auto GetCountResult() const -> long {
     return query_count;
   }
 
@@ -390,7 +379,7 @@ public:
   }
 
   /**
-   * Get a JSON representation of the respone.
+   * Get a JSON representation of the response.
    *
    * For debugging.
    */