[DRIVERS-2241] Wording to add usage and API information for the csfle…

… dynamic library (#1165)

* Warning-free build with Sphinx 4

* Documenting csfle library loading for client-side-encryption

* Annotate most references to `csfle`. Finish doc changes that refer to mongocryptd

* Note csfle in the bson subtype6 doc

* Clean up accidental whitespace changes, remove cross-doc link targets (for now)

* Merge dual search paths, prefer to use that to "disable" csfle

* Install Sphinx to allow recognition of additional text roles by rstcheck

* Option "csfleRequired" to fail CSE initialization if csfle is not available.

* Spelling and punct and wording

* [DRIVERS-2241] Minimal changeset for specifying csfle behavior

* Spelling

* Remove csfleSearchPaths. Just use the system-search

* Tweak override path option key to match spec

* Note search paths as an API available for driver testing, but not the user API.

* Remove "disabling" csfle as a user-facing option. Note how a driver can disable csfle for testing purposes

.github/workflows/rstcheck.yml

@@ -19,7 +19,7 @@ jobs:
       - name: Install dependencies
         run: |
           python -m pip install --upgrade pip
-          pip3 install rstcheck==3.3.1
+          pip3 install rstcheck==3.3.1 sphinx==4.5.0
       - name: Check RST files with rstcheck
         run: |
           rstcheck -r source/ --ignore-language c,python,java --report error