`Quill.getText()` is allowed to be called with no arguments, since it
[defaults][1] to returning the whole document.

However, the overload declarations require arguments, resulting in a
compilation error when trying to call `getText()` with no arguments:

```
(method) Quill.getText(range: {
    index: number;
    length: number;
}): string (+1 overload)
Expected 1-2 arguments, but got 0.ts(2554)
```

This change makes all the arguments in the overloads optional to match
the implementation.

[1]: https://github.com/quilljs/quill/blob/d2f689fb4744cdada96c632a8bccf6d476932d7b/core/quill.ts#L501-L502

The `Block` blot inherits from `parchment`'s `ParentBlot`, where the
`ref` argument [is optional][1].

This change updates the `Block` signature to match its parent.

[1]: https://github.com/quilljs/parchment/blob/634e50f4d73a3351952250146510332dbc0af961/src/blot/abstract/parent.ts#L238

`Quill.getFormat()` is allowed to be called with no arguments, since it
[defaults][1] to just getting the current selection.

However, the overload declarations require arguments, resulting in a
compilation error when trying to call `getFormat()` with no arguments:

```
(method) Quill.getFormat(index: number, length?: number): any (+1 overload)
Expected 1-2 arguments, but got 0.ts(2554)
```

This change makes all the arguments in the overloads optional to match
the implementation.

[1]: https://github.com/quilljs/quill/blob/d2f689fb4744cdada96c632a8bccf6d476932d7b/core/quill.ts#L435

`Clipboard.dangerouslyPasteHTML()` is allowed to be called without an
index as its first argument.

At the moment, doing this results in a compilation error:

```
(method) Clipboard.dangerouslyPasteHTML(index: number, html: string, source?: EmitterSource): void
Expected 2-3 arguments, but got 1.ts(2554)
```

This change adds the overload to allow this.

Consider a document with a single piece of bold text. As a `Delta`, this
would be represented as:

```js
const doc = new Delta().insert('a', {bold: true})
```

Now consider the following `Delta` being applied:

```js
const delta = new Delta().insert('\n1')
```

The above `Delta` will:

  - prepend the document with a newline
  - follow that newline with an **unformatted** string

Indeed, using `doc.compose(delta)` yields:

```js
const result = new Delta()
  .insert('\n1')
  .insert('a', {bold: true})
```

However, the same result is not reached when using the Quill
`editor.applyDelta()`, which instead results in bold formatting being
incorrectly applied to our unformatted string:

```js
const badResult = new Delta()
  .insert('\n')
  .insert('1a', {bold: true})
```

This happens because Quill does an insert of the whole insertion, but
doesn't handle the line splitting.

This change fixes this issue by splitting ops on newlines, and handling
them separately, which applies the correct formatting.

At the moment we try to reassign `lines: Blot` and `leaves: Blot` to
`lines: {}` and `leaves: {}`.

This change just creates new variables, so that we don't have these
compiler errors.

At the moment, since `@ts-expect-error` [doesn't apply][1] to type
definitions, we get a downstream compilation error:

```
TS2416: Property 'addModule' in type 'BaseTheme' is not assignable to the same property in base type 'Theme'.
  Type '(name: string) => unknown' is not assignable to type '{ (name: "clipboard"): Clipboard; (name: "keyboard"): Keyboard; (name: "uploader"): Uploader; (name: "history"): History; (name: "selection"): Selection; (name: string): unknown; }'.
    Type '{}' is missing the following properties from type 'Clipboard': matchers, addMatcher, convert, convertHTML, and 8 more.

10     addModule(name: string): unknown;
```

This change updates the `Base` class to have the same signature as
for `addModule()` as its parent class.

[1]: microsoft/TypeScript#38628

At the moment, the `BaseTooltip.edit()` signature has type:

```ts
declare class BaseTooltip extends Tooltip {
  edit(mode?: string, preview?: null): void;
}
```

This change tweaks the signature to be more accurate:

```ts
declare class BaseTooltip extends Tooltip {
  edit(mode?: string, preview?: string | null): void;
}
```

Improve inserting performance

* Pass source for history actions

Since undo, redo emitted by user the source should USER.

* Add tests for history.undo()/redo()

---------

Co-authored-by: Zihua Li <i@zihua.li>

Migrate tests to Vitest

Closes #3779

In RFC the sizes can be negative when the origin is at the right/bottom side,
to address this, we use abc() to get the expected value.

Co-authored-by: Claire Fields <clairefields15@gmail.com>