feat(diagnosticts): add option to show the source of the entry

[Koliras]

Description

Adds option to show LSP source to diagnostics picker.
It's useful when you work on a multilanguage project.

Fixes #2544
Fixes #2110

Type of change

• New feature (non-breaking change which adds functionality)
• This change requires a documentation update

How Has This Been Tested?

• :lua require('telescope.builtin').diagnostics({ show_source = true })

In the end of every result there should be the source that created the entry

Configuration:

• Neovim version (nvim --version): v0.10.2
• Operating system and version: Ubuntu 24.04.1 LTS

Checklist:

• My code follows the style guidelines of this project (stylua)
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation (lua annotations)