fix: Hive max length bug

[murali-shris]

fixes: #1863
- What I did

• Fixed issue in persistence layer for keys with length greater than max length suppported in hive(currently 255)
  - How I did it
• Added max length check in put, putAll and create methods in HiveKeyStoreImpl
• added unit tests
  - How to verify it
• units tests should pass
• point to persistence branch and run at_client and server tests
  fix: test persistence for hive max key length check at_client_sdk#1281
  fix: test persistence for hive key length check #1877

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With this fix, server will return data:null when updating key with length > 255 chars. Have to make fix in server to return correct error message.

[gkc]

Should we restrict the length to 248 if it doesn't start with "cached:"? Leaves enough for a "cached:"prefix to be added on a caching atServer / client

[murali-shris]

Should we restrict the length to 248 if it doesn't start with "cached:"? Leaves enough for a "cached:"prefix to be added on a caching atServer / client

sure Gary.

[murali-shris]

Should we restrict the length to 248 if it doesn't start with "cached:"? Leaves enough for a "cached:"prefix to be added on a caching atServer / client

sure Gary.

@gkc I had a discussion with @sitaram-kalluri on this.
Let's say the key is @ bob: phone@ alice. This will be stored in alice's keystore. If the key has ttr, then @ bob will cache the key at his end. 255 char limit will be enforced at bob's keystore including cached:
In persistence layer, 255 can be the max limit
in client/server, 248 without cached: and 255 including cached:
is this fine?

[gkc]

Should we restrict the length to 248 if it doesn't start with "cached:"? Leaves enough for a "cached:"prefix to be added on a caching atServer / client

sure Gary.

@gkc I had a discussion with @sitaram-kalluri on this. Let's say the key is @ bob: phone@ alice. This will be stored in alice's keystore. If the key has ttr, then @ bob will cache the key at his end. 255 char limit will be enforced at bob's keystore including cached: In persistence layer, 255 can be the max limit in client/server, 248 without cached: and 255 including cached: is this fine?

Yes I believe so

[gkc]

For readability, instead of long string of letters unclear as to what length they are, can we instead create and use a function which returns a random string of whatever length is required

[murali-shris]

Done