feature: added export dotenv-plain

[micahco]

Description 📣

This PR adds a new format option to the CLI: infisical export -f dotenv-plain.

The default dotenv format wraps the values in singles quotes (KEY='value') which can cause issues when feeding secrets from Infisical into a Docker container using the --env-file flag of docker run command. For example, when running the bluenviron/mediamtx container, I received the following error message (notice the extraneous single quotes wrapping the value):

$ docker run --rm -it --network=host --env-file <(infisical export) bluenviron/mediamtx
ERR: invalid source: ''rtsp://server/mystream''

Currently, I am using the --template flag to workaround this issue:

$ docker run --rm -it --network=host --env-file <(infisical export --template="/path/to/template/file") bluenviron/mediamtx

my-template-file:

{{$secrets := secret "<infisical-project-id>" "<environment-slug>" "<folder-path>"}}
{{- with $secrets }}
{{- range $index, $secret := . }}
{{ $secret.Key }}={{ $secret.Value }}
{{- end }}
{{- end }}

Type ✨

• Bug fix
• New feature
• Improvement
• Breaking change
• Documentation

Tests 🛠️

The changes have been tested by running the application and confirming the expected output.

$ go run main.go export -f dotenv-plain
...
KEY_1=value_1
KEY_2=value_2
...

---

• I have read the contributing guide, agreed and acknowledged the code of conduct. 📝