Create in memory data store/graph store with at least max_points as 1

[ltan1ms]

• [ ] Does this PR have a descriptive title that could go in our release notes?
• [ ] Does this PR add any new dependencies?
• [ ] Does this PR modify any existing APIs?
  • [ ] Is the change to the API backwards compatible?
• [ ] Should this result in any changes to our documentation, either updating existing docs or adding new ones?

Reference Issues/PRs

What does this implement/fix? Briefly explain your changes.

This fix the issue where when max_points passed is 0, it should use 1 to align with the logic in the other class constructor it calls into: https://github.com/microsoft/DiskANN/blob/main/src/index.cpp#L67-L69

Otherwise, the code will assume the underlying in memory block has 1 more than actual capacity and causes memory heap corruption as seen in my debugging:

Any other comments?

[harsha-simhadri]

" it should use 1" -- for which variable?

[ltan1ms]

" it should use 1" -- for which variable?

oops, there was a typo in my PR description. it's the "max_points"