Refactor init cmd

[terzioglub]

Old Process:
For Every Initialized Template:

A separate .bruin.yml file was created inside the template, even if one already existed elsewhere.

New Process:

task: running bruin init with template X

if current folder is git repo:
if .bruin.yml exist in current folder:
merge .bruin.yml from current folder with the one from template X
else:
create .bruin.yml in current folder from contents of .bruin.yml of template X
create folder X in current folder with pipeline contentx except the .bruin.yml
else (current foder is not git repo):

go up the folder tree structure until we find a git repo or we reach the very root of the file system

if we reach the very root of the filesystem:
    create "bruin" folder
    init git repo in "bruin" folder
    create .bruin.yml based on the template X and place bruin folder
    create folder X inside bruin folder

else (if we reach an existing git repo in the ancestors in folder Y):
    do we also find a .bruin.yml:
        merge .bruin.yml of pipeline X with the one in folder Y
        create folder X with contents of the pipeline except for .bruin.yml (since we mertged)
    else:
        create .bruin.yml in folder Y based on the one from pipeline X
        create folder X with contents of the pipeline except for .bruin.yml 

[karakanb]

two notes:

• let's add an integration test that covers the changes here.
• make sure we are not overriding if there are existing connections with the same name.

[karakanb]

let's say the user has two envs, staging and prod, staging being marked as the default. if we have a .bruin.yml in our template and that has an env called default, it seems like we would create it as a new environment, correct? in that case I suggest using the user's default environment and merge into that.