Allow `FList` to store `MultiPack` entries

[Pushkar-Bhuse]

This PR adds a functionality mentioned in the comments of #900.

Description of changes

In this PR, we modify the interface of FList to store and process MultiPack entries. Currently, these are mainly used by the MultiPackGroup entry to store group members. The way this happens is that for MultiPack entries, we store them as a tuple of the tid of the entry and the tid of the DataPack the entry is associated with.

Possible influences of this PR.

We can now store MultiPack entries in FList now, something that was not not possible earlier.

Test Conducted

Describe what test cases are included for the PR.

[codecov[bot]]

Codecov Report

Merging #902 (d62e957) into master (d5869b3) will decrease coverage by 0.03%. The diff coverage is 50.00%.

@@            Coverage Diff             @@
##           master     #902      +/-   ##
==========================================
- Coverage   80.91%   80.87%   -0.04%     
==========================================
  Files         253      253              
  Lines       19618    19619       +1     
==========================================
- Hits        15874    15867       -7     
- Misses       3744     3752       +8     

Impacted Files	Coverage Δ
forte/data/ontology/core.py	80.22% <38.88%> (-2.25%)	:arrow_down:
forte/data/ontology/top.py	78.10% <100.00%> (-0.64%)	:arrow_down:

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