Update reference/configuration/framework.rst

This PR is related to this one https://github.com/symfony/symfony/pull/5347.
Update reference/dic_tags.rst

Adding tags to the tag list reference
Update reference/configuration/framework.rst

Changing backticks
add cookbook entry on creating dynamic forms based on services
camelCase variable names
complete config for form as a service
consistent use of DemoBundle instead of 'WhateverBundle'
Update reference/configuration/framework.rst

The GetSetMethodNormalizer is not loaded by default
merged all dynamic form articles in one. Added a section on advanced form configuration
PHP5.3 syntax for arrays
Updated .gitignore to ignore Sphinx files
Bootstrapped Form component chapter
Introduction chapter for the Form component
[WIP][#1883] Adding more and more details for the form introduction

Still a WIP because:

a) Bernhard will certainly need to review it
b) I would like to re-read it - I felt that there are still gaps - too many details here, too few details there
c) This is part of a larger, on-going project to refactor the forms docs
d) We need to bootstrap the validation and translation component docs, and other things need to be refactored to make sense
[Form] Making updates per @bschussek and fixing some markup issues
Added a section on the BCrypt password encoder.
A cookbook article on how to test forms
Remove --dev, replace AbstractType by FormTypeInterface
Add missing semicolon
Removing .gitignore file - putting the sphinx build files right in this directory is just one option