Insert with specific unique constraint (#56)

* initial working upsert with custom key

* Add insert with custom unique for all tables

* update primary key version to use parameter pack

* fix snapshot

* wip

* wip

* wip

* wip

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* wip

---------

Co-authored-by: Stephen Celis <[email protected]>

Author: rcarver

Sources/StructuredQueriesCore/Documentation.docc/Articles/DefiningYourSchema.md

@@ -189,12 +189,12 @@ and will decode data from the database using the `RawRepresentable` conformance
 @Row {
   @Column {
     ```swift
-    Reminder.insert(
+    Reminder.insert {
       Reminder.Draft(
         title: "Get haircut",
         priority: .medium
       )
-    )
+    }
     ```
   }
   @Column {
@@ -240,12 +240,12 @@ With that you can insert reminders with notes like so:
 @Row {
   @Column {
     ```swift
-    Reminder.insert(
+    Reminder.insert {
       Reminder.Draft(
         title: "Get groceries",
         notes: ["Milk", "Eggs", "Bananas"]
       )
-    )
+    }
     ```
   }
   @Column {
@@ -342,9 +342,9 @@ And StructuredQueries will take care of formatting the value for the database:
 @Row {
   @Column {
     ```swift
-    Reminder.insert(
+    Reminder.insert {
       Reminder.Draft(date: Date())
-    )
+    }
     ```
   }
   @Column {

Sources/StructuredQueriesCore/Documentation.docc/Articles/GettingStarted.md

@@ -305,7 +305,7 @@ capable of. See <doc:SelectStatements> for more examples of select statements, a
 The library provides the tools necessary to construct type-safe insert statements in SQL, including
 inserting an entire value into a table, inserting only a subset of rows, as well as what to do on
 conflicts. Using the `Reminder` data type from above, we can insert data for all of its rows using
-the  ``Table/insert(or:_:values:onConflict:)`` method:
+the  ``Table/insert(or:_:values:onConflict:where:doUpdate:where:)`` method:
 
 @Row {
   @Column {
@@ -338,10 +338,11 @@ mechanism). The second trailing closure is a list of values that you want to ins
 and the number of columns and data type of each column must match what is specified in the first
 trailing closure.
 
-You can provide a 3rd trailing closure to ``Table/insert(or:_:values:onConflict:)`` to describe what
-to do in case there is a conflict while inserting data. For example, suppose we had a unique index
-on the "title" column of the reminders table. Then when inserting a value with a repeated title we
-could resolve the conflict by appending the string `" (Copy)"` to the title:
+You can provide a 3rd trailing closure to
+``Table/insert(or:_:values:onConflict:where:doUpdate:where:)`` to describe what to do in case there
+is a conflict while inserting data. For example, suppose we had a unique index on the "title" column
+of the reminders table. Then when inserting a value with a repeated title we could resolve the
+conflict by appending the string `" (Copy)"` to the title:
 
 @Row {
   @Column {