[BUG] Add secret to file should keep existing formatting

[lucas-dclrcq]

Describe the bug

If I have a file containing secrets plus some comments like the following :

# Work stuff
super_secret = "pouet"

# Personal stuff
reddit_password = "incrackable"

If use the command bombadil add secret -f myfile.toml I will loose the comments and manual sorting of the secrets.

Proposal : just append the secret at end of file.