Introduce config support to each bench.

[Xieyt]

• Support configuration of fm created bench using a config file.
• The config file name will be bench_config.toml will stored in root of each bench.
• Config file will be created after each bench creation.
• As of now bench_config.toml supports this attributes:

# name of the site
name = "example.com"

# when true enables frappe developer mode
developer_mode = false

# when true enables admin tools mode
admin_tools = false

# "prod" -> for bench prod environment
# "dev"  -> for bench dev environment
environment_type = "prod"

# enable ssl if defined
[ssl]
# ssl_type -> "letsencrypt" / "disable"
ssl_type = "letsencrypt"
# only applicable if ssl_type is "letsencrypt"
hsts = "off"
# only applicable if ssl_type is "letsencrypt"
email = "exampl@example.com"