Improve expansion rules for french intents

[piitaya]

Co-worked with @jlpouffier to improve expansions rules

1. Remove variable names from every expansion rules to have better readability of each sentence

Before

sentences: 
  - allume la lumière dans <area>

Area variable is hidden in the expansion rule
After

sentences: 
  - allume la lumière dans [<le>]{area}

Area variable is now explicit in the sentence

2. Remove the fully optional expansion rules, so that we have more flexibility and readability

Before

sentences: 
  - allume la lumière dans <le>{area}

We don't know that "le" is optional because it's hidden in the expansion rule

After

sentences: 
  - allume la lumière dans [<le>]{area}

We know that "le" is optional because it's explicit in the sentence

3. Disambiguate words with accent

Before

expansion_rules:
  fenetre: "(fen(e|ê)tre[s]|baie[s]|v(e|é)lux|lucarne[s])"

After

expansion_rules:
  fenetre: "(fenetre[s]|fenêtre[s]|baie[s]|velux|vélux|lucarne[s])"

[jlpouffier]

👍🏻