Use NV indexes to store node's seed in TPM

[samuelmanzanera]

Description

Leverage TPM NV indexes to store the node seed generated by secure random generator from the TPM.
This allows to provide a secure backup for the node seed.

Fixes #589

Type of change

Please delete options that are not relevant.

• New feature (non-breaking change which adds functionality)

How Has This Been Tested?

Start a node with TPM activated.
Then reboot and restart the app, the seed should remain the same.

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules