feat!: update get from (V, error) to (V, bool) (#20)

## Description

Currently, the signature for `Table.Get` is `func (K) (V, error)`. This is not very Go-idiomatic, which prefers to return a boolean instead of an error. For instance, a built-in Go map is used like so:

```go
if value, ok := users[id]; !ok {
  // ...
}
```

Updating our table to look like that is best practice. In that same vein, to support direct lookup (i.e. `v := users[id]`), this PR also adds `Table.Find`.

## Changes

- BREAKING CHANGE: Update contract of `Table.Get` to `func (K) (V, bool)`. Returns 'false' is the item cannot be found, and 'true' if it is found.
- Add `Table.Find`.
- Updated tests and documentation to match the change.

### Design Decisions

- Chose to make this decision because throwing an error implies that there is something 'wrong' with the table. There is nothing wrong with the table; it is just that the item does not exist.

## Checklist

- [x] Tests pass
- [x] Docs updated

Reviewed-on: #20
Co-authored-by: M.V. Hutz <git@maximhutz.me>
Co-committed-by: M.V. Hutz <git@maximhutz.me>

table.go

@@ -95,24 +95,31 @@ func (t *Table[K, V]) shrink() error {
 	return t.resize(t.bucketA.capacity / t.growthFactor)
 }
 
-// Get fetches the value for a key in the [Table]. Returns an error if no value
-// is found.
-func (t Table[K, V]) Get(key K) (value V, err error) {
+// Get fetches the value for a key in the [Table]. Matches the comma-ok pattern
+// of a builtin map; see [Table.Find] for plain indexing.
+func (t Table[K, V]) Get(key K) (value V, ok bool) {
 	if item, ok := t.bucketA.get(key); ok {
-		return item, nil
+		return item, true
 	}
 
 	if item, ok := t.bucketB.get(key); ok {
-		return item, nil
+		return item, true
 	}
 
-	return value, fmt.Errorf("key '%v' not found", key)
+	return
+}
+
+// Find fetches the value of a key. Matches direct indexing of a builtin map;
+// see [Table.Get] for a comma-ok pattern.
+func (t Table[K, V]) Find(key K) (value V) {
+	value, _ = t.Get(key)
+	return
 }
 
 // Has returns true if a key has a value in the table.
 func (t Table[K, V]) Has(key K) (exists bool) {
-	_, err := t.Get(key)
-	return err == nil
+	_, exists = t.Get(key)
+	return
 }
 
 // Put sets the value for a key. Returns error if its value cannot be set.