[GOBBLIN-2138] added loadTable api method in baseicebergcatalog

[Blazer-007]

Dear Gobblin maintainers,

Please accept this PR. I understand that it will not be reviewed until I have checked off all the steps below!

JIRA

• [✔️ ] My PR addresses the following GOBBLIN-2138 issues

Description

• [✔️ ] Here are some details about my PR, including screenshots (if applicable):
  • Table interface provides some api like newReplacePartitions() and new Overwrite() which are not present in tableOperations, so the object of this needs to be created from catalog using loadTable() api of catalog implementation, for that a simple abstract method in BaseIcebergCatalog is added.

Tests

• [✔️ ] My PR adds the following unit tests OR does not need testing for this extremely good reason:
  • Doesn't need any tests, will be adding tests when IcebergTable.java classes will be using this Table instance

Commits

• [✔️ ] My commits all reference JIRA issues in their subject lines, and I have squashed multiple commits if they address the same issue. In addition, my commits follow the guidelines from "How to write a good git commit message":
  1. Subject is separated from body by a blank line
  2. Subject is limited to 50 characters
  3. Subject does not end with a period
  4. Subject uses the imperative mood ("add", not "adding")
  5. Body wraps at 72 characters
  6. Body explains "what" and "why", not "how"