feat: prettierrc

[rbalet]

Description

• Add the .prettierrc file
• create a new npm run prettier script
• Add prettier as devDependencies

Note

npx prettier --write . or npm run prettier have to be run in another pull-request.

[rbalet]

@ihym Hey, I did already this first PR.

I did not run npx prettier --write . as I would like to let you do it and do a PR on your side.
Doing so will change a lot of lines across the entire codebase while not doing any change in the logic.

So I feel it more logical to let your name on such commit.
(I could git ignore the blame, but I would need to add a new file, so if we can avoid ; )

Let me know,
I'll do the rest of the PRs for the migration on each Angular version after this get merged.

Cheers