Move mbedtls_dev to mbedtls-framework

[ronald-cron-arm]

Move all scripts in scripts/mbedtls_dev to scripts/mbedtls_framework in mbedtls-framework.

• In an independent mbedtls PR, rename mbedtls_dev to mbedtls_framework
• Move files while keeping their mbedtls history (same commits). It has been suggested/discussed to create a commit in mbedtls where all files are removed but the mbedtls_dev/mbedtls_framework ones and then merge the commit using git merge --allow-unrelated-histories to add the files in mbedtls_framework. Any issue with that approach? Check that once done with a set of files, it can be done subsequently with other set of files.

[davidhorstmann-arm]

I've written a script in Mbed-TLS/mbedtls-docs#145 that should be able to create branches in this way and do the renaming in one step. I'll try applying this to get a PR