Merged PR 1767879: [RUM] Support & improve debugging the RUM index

### Does this PR have any customer impact?
No

### Type (Feature, Refactoring, Bugfix, DevOps, Testing, Perf, etc)
Testing

### Does it involve schema level changes? (Table, Column, Index, UDF, etc level changes)
Yes

### Are you introducing any new config? If yes, do you have tests with and without them being set?
No
### ChangeLog (Refer [Template](../oss/CHANGELOG.md))

### Description

Support reading and introspecting the RUM index.

Add extension functions similar to those for btree in pageinspect that allow the user to read and evaluate how the RUM index is internally structured.

- Read out the meta page info
- Read out the page stats (number of entries, flags etc)
- Read out the page entries for entry pages
- Read out data entries from data pages

Sample output:
![image.png](https://dev.azure.com/msdata/ba574a88-a171-48e0-8fcb-5fef6d23739c/_apis/git/repositories/501a5e7e-ffdc-4d1e-a5e6-910f73c6eb9a/pullRequests/1767879/attachments/image.png)

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#### AI description  (iteration 1)
#### PR Classification
This pull request implements a new feature to enhance debugging support for the RUM index.

#### PR Summary
The changes add comprehensive debugging utilities for the RUM index by implementing new C routines and exposing them as SQL UDFs. This improves the ability to inspect meta page information, page statistics, and index entries in JSON format.
- Added new debugging source files in `oss/internal/pg_documentdb_extended_rum/src/rum_debug.c` and `pgmongo_rum/src/rum_debug.c` to output meta information, stats, and entry details.
- Introduced new SQL UDFs in `pgmongo/sql/udfs/rum/rum_index_debug_functions--1.107-0.sql` and `--latest.sql` that wrap the C functions.
- Updated the public API schema expected output and modified the `pgmongo_rum/Makefile` to compile the new debugging routines.
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Author: visridha