feat: tpl identitySchemas files

[dro-sh]

Use Helm tpl function to substitute file from values. Closes #505

I would like to write identities schema on separate file, not on .Values.kratos.identitySchemas.<filename>.<json-schema>. Json schema locales on same directory which my values on. It allows me to use hints from my IDE. More details on linked issue

Related Issue or Design Document

With PR linked to #505 issue. I use Helm tpl function to substitute template to file which are set using --set-file Helm CLI argument. Example described on issue

Checklist

• [x] I have read the contributing guidelines and signed the CLA.
• [ x I have referenced an issue containing the design document if my change introduces a new feature.
• [x] I have read the security policy.
• [x] I confirm that this pull request does not address a security vulnerability. If this pull request addresses a security vulnerability, I confirm that I got green light (please contact security@ory.sh) from the maintainers to push the changes.
• [ ] I have added tests that prove my fix is effective or that my feature works. N/A Testing using helm install
• [x] I have added necessary documentation within the code base (if appropriate).

Further comments

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