Goals for this task:

1. Introduce new file aggregate_expression_intender_text.h/.cpp. Look at aggregate_expression_intender.h as an example.
2. In this new file, implement the function markTextSearch() (look at markEquality()).method markTextSearch(). This function should be called from aggregate_expression_intender::mark().
3. Implement a new walker specialization TextIntentionWalker.
4. Modify aggregate_expression_intender::Subtree::Compared so it can keep either the text search operator, or the encryption placeholder context (TBD). This is required because later on, we need a way to pass down the operator to our call to buildEncryptPlaceholder.
5. Implement a specialization of IntentionPreVisitorBase, which visits ExpressionEncStrStartsWith.
6. Implement visit(ExpressionEncStrStartsWith*) in IntentionInVisitorBase.
7. Implement visit(ExpressionEncStrStartsWith*) in IntentionPostVisitorBase.

This item expects that SERVER-101139 is complete, as it implements the required changes to serialize the correct placeholder when provided with the corresponding EncryptionPlaceholderContext. 

Performing the above items should result in the constant literal value in ExpressionEncStrStartsWith being replaced with the placeholder.

Testing:

1. Sanity check test, can we add a test in fle/agg.js or fle/find.js which checks that we can't use $encStrStartsWith  a FLE1 encryption schema?
2. Expression_analysis_test.cpp: Add test to EvaluatedExpressionsCorrectlyReturnNotEncrypted which checks that new expressions return an unencrypted value (i.e evaluates to bool).
3. Fle_match_expression_test.cpp: Here we can add unit tests for checking that ExpressionEncStrStartsWith gets replaced with a placeholder by FLEMatchExpression.

We can add query analysis jstests in a follow-up ticket.