Introduce new method `ConcatSourceMapBuilder::from_sourcemaps`.
Where all the sourcemaps being concatenated exist at time that you
create `ConcatSourceMapBuilder`, it's faster to use `from_sourcemaps`,
because it pre-allocates enough space for the data it will hold and so
avoids memory copying.
Before:
```rs
let mut builder = ConcatSourceMapBuilder::default();
builder.add_sourcemap(&sourcemap1, 0);
builder.add_sourcemap(&sourcemap2, 100);
builder.add_sourcemap(&sourcemap3, 100);
let combined = builder.into_sourcemap();
```
After:
```rs
let builder = ConcatSourceMapBuilder::from_sourcemaps(&[
(&sourcemap1, 0),
(&sourcemap2, 100),
(&sourcemap3, 200),
]);
let combined = builder.into_sourcemap();
```
Make 2 changes to sourcemap benchmark:
1. Move counting line breaks in output text to outside of the measured loop. This operation is reasonably expensive, and isn't part of what we're trying to measure.
2. It looks like benchmark is trying to measure concatenating 2 source maps, but `for i in 0..1` was actually only concatenating 1.
This PR introduces two type alias to avoid the confusing const generic `pub struct Codegen<'a, const MINIFY: bool>`
* CodeGenerator - Code generator without whitespace removal.
* WhitespaceRemover - Code generator with whitespace removal.
Usage is changed to a builder pattern:
```rust
CodeGenerator::new()
.enable_comment(...)
.enable_sourcemap(...)
.build(&program);
```
The sourcemap implement port from
[rust-sourcemap](https://github.com/getsentry/rust-sourcemap), but has
some different with it.
- Encode sourcemap at parallel, including quote `sourceContent` and
encode token to `vlq` mappings.
- Avoid `Sourcemap` some methods overhead, like `SourceMap::tokens()`
caused extra overhead at common cases. Here using `SourceViewToken` to
instead of it.
