(DOCSP-30689): Update Kotlin version source constant (#102)

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After Java v4.10 is released, Java and Kotlin will be versioned
together, so the extra source constant is unneeded.

This PR updates the following:
- Remove `api-kotlin` source constant
- Update all links to use `api` constant that points to version 4.10
- Remove `version-next` constant
- Increment `version` to `4.10`

To be merged and deployed after Java v4.10 is released and API docs are
updated (i.e. Java API ref links point to v4.10 URL)

JIRA - https://jira.mongodb.org/browse/DOCSP-30689
Staging -
https://docs-mongodbcom-staging.corp.mongodb.com/kotlin/docsworker-xlarge/docsp-30689-constant/

- [ ] Is this free of any warnings or errors in the RST?
- [ ] Did you run a spell-check?
- [ ] Did you run a grammar-check?
- [ ] Are all the links working?

(cherry picked from commit 298b164)

Author: cbullinger

source/fundamentals/databases-collections.txt

@@ -28,9 +28,8 @@ With the MongoDB Kotlin driver, data can be modeled using Kotlin data classes or
 `Document <{+api+}/apidocs/bson/org/bson/Document.html>`__ class
 to store and retrieve data from MongoDB.
 
-.. TODO:(DOCSP-29224): add back in when document data format data classes are documented
-.. To learn more about using data classes to store and retrieve data, refer to
-.. :ref:`Document Data Format: Data Classes <fundamentals-data-classes>`.
+To learn more about using data classes to store and retrieve data, refer to
+:ref:`Document Data Format: Data Classes <fundamentals-data-classes>`.
 
 Access a Database
 -----------------
@@ -69,8 +68,6 @@ The following example accesses a collection named "testCollection" from a
    MongoDB implicitly creates the collection when you first insert data
    into that collection.
 
-<<<<<<< HEAD
-=======
 .. _db-coll-specify-return-type:
 
 Specify Return Type
@@ -113,7 +110,6 @@ document with a ``name`` value of ``"strawberry"``:
 
       NewFruit(id=1, name=strawberry, quantity=205, seasons=[summer, fall])
 
->>>>>>> 298b164 ((DOCSP-30689): Update Kotlin version source constant (#102))
 Create a Collection
 -------------------