experimenting with inline snapshot support

[gkampitakis]

The api right now looks like

Calling the first time

t.Run("my test", func(t *testing.T) {
user := struct{ Name string }{
	Name: "george",
}

snaps.MatchInlineSnapshot(t, user, nil)
})

and then it will populate with the snapshot data

t.Run("my test", func(t *testing.T) {
user := struct{ Name string }{
	Name: "george",
}

snaps.MatchInlineSnapshot(t, user, snaps.Inline("struct { Name string }{Name:\"george\"}"))
})

Still haven't investigated all the edge cases that this can have and I can see being useful but not sure how much is it worth it.

Two issues that are not addressed

• Long line snapshots, haven't found a way to split text to multiples lines
  - I believe jest doesn't address it at all. I want to also have a look how it's handled by insta.
• Comments ast parsing.
  - I have seen some weird behaviours, but nothing major. I want to test further.
• Currently there is an issue with the current approach. If a file has multiple InlineSnapshots and updated at the same time the file lines can be moved breaking the "write". I am investigating ways to fix this.
• I want to run tests to make concurrent (t.Parallel) safe.

closes #110