Enhancement: Added support for templates in external secrets

[pawan-mehta-dt]

🔖 Feature description

Add support for templates in external secrets

🎤 Pitch / Usecases

In our case we modify the format in which we receive secrets from aws secrets manager and then use it in our application, we achieve this using ESO template engine - https://external-secrets.io/latest/guides/templating/

Devtron ESO yaml doesn't support it, Support for this will enable whole lot of possibilities for data manipulation before adding it to the application

Extra Configurations support needed on UI:

• Need support for .esoSecretData.esoDataFrom and .esoSecretData.template. Right now, only .esoSecretData.esoData is supported
• Remove validation for secretKey and key, validation can be added on either esoData or esoDataFrom is needed
• Open a field for subPath as we have in Mount External Secret (it can be optional if using esoData and required if using esoDataFrom)

🔄️ Alternative

Deploy external secrets using rawYaml or use an initContainer to resolve the issue

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• [X] I checked and didn't find similar issue

🏢 Have you read the Code of Conduct?

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