Add substr and aes_cbc DSL functions

[hktalent]

1. Added substr helper for Add substr DSL function #2304 By @hktalent

substr('xxtestxxx',2) ==  "testxxx"
substr('xxtestxxx',2,-2)  == "testx"
substr('xxtestxxx',2,6)  == "test"

2. add DSL aes_cbc for helper function for aes_cbc encryption #2243 By @hktalent

aes_cbc("key111key111key111key111", "dataxxxxxxdataxxxxxxdataxxxxxxdataxxxxxxdataxxxxxx")

Proposed changes

Checklist

• Pull request is created against the dev branch
• All checks passed (lint, unit/integration/regression tests etc.) with my changes
• I have added tests that prove my fix is effective or that my feature works
• I have added necessary documentation (if appropriate)

[forgedhallpass]

Hello @hktalent,

Thank you for your work. Our team will review the changes.

Note: we can accept it this way now, but generally, it is recommended to create separate PRs for different tickets.
In order to achieve that, you might need to create separate branches on your fork.
That, together with test cases helps closing PRs faster.

[Mzack9999]

Temporary commented out TestGetPrintableDslFunctionSignatures (#2473)