[WIP] Improve serialization also for legacy database versions

[Viatorus]

PR Checklist

Please check if your PR fulfills the following requirements:

• [ ] The commit message follows our guidelines: https://github.com/LokiJS-Forge/LokiDB/blob/master/CONTRIBUTING.md#commit
• [ ] Tests for the changes have been added (for bug fixes / features)
• [ ] Docs have been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

[ ] Bugfix
[ ] Feature
[ ] Code style update (formatting, local variables)
[ ] Refactoring (no functional changes, no api changes)
[ ] Build related changes
[ ] CI related changes
[ ] Documentation content changes
[ ] Other... Please describe:

What is the current behavior?

Issue Number: N/A

What is the new behavior?

Does this PR introduce a breaking change?

[ ] Yes
[ ] No

Other information

[coveralls]

Pull Request Test Coverage Report for Build 674

• 122 of 126 (96.83%) changed or added relevant lines in 7 files are covered.
• 2 unchanged lines in 1 file lost coverage.
• Overall coverage increased (+0.4%) to 88.152%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
packages/loki/src/collection.ts	15	16	93.75%
packages/loki/src/serialization/migration.ts	21	24	87.5%
<!--	Total:	122	126

Files with Coverage Reduction	New Missed Lines	%
packages/loki/src/loki.ts	2	91.84%
<!--	Total:	2

Totals
Change from base Build 629:	0.4%
Covered Lines:	3486
Relevant Lines:	3759

---

💛 - Coveralls

[Viatorus]

See #53 for conversation.

[codecov[bot]]

Codecov Report

Merging #113 into master will decrease coverage by 25.1%. The diff coverage is 96.87%.

@@            Coverage Diff             @@
##           master    #113       +/-   ##
==========================================
- Coverage    92.4%   67.3%   -25.11%     
==========================================
  Files          32      34        +2     
  Lines        3726    6578     +2852     
==========================================
+ Hits         3443    4427      +984     
- Misses        283    2151     +1868

Impacted Files	Coverage Δ
packages/full-text-search/src/full_text_search.ts	100% <ø> (ø)	:arrow_up:
packages/lokijs/lokijs.js	32.8% <ø> (ø)
packages/loki/src/clone.ts	90.19% <ø> (ø)	:arrow_up:
packages/indexed-storage/src/indexed_storage.ts	48.88% <ø> (ø)	:arrow_up:
packages/loki/src/result_set.ts	95.11% <100%> (+0.03%)	:arrow_up:
packages/loki/src/dynamic_view.ts	87.54% <100%> (+4.34%)	:arrow_up:
...s/partitioning-adapter/src/partitioning_adapter.ts	99.08% <100%> (ø)	:arrow_up:
packages/loki/src/loki.ts	98.55% <100%> (+0.74%)	:arrow_up:
packages/full-text-search/src/inverted_index.ts	100% <100%> (ø)	:arrow_up:
packages/loki/src/serialization/migration.ts	87.5% <87.5%> (ø)
... and 5 more

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