chore: refactor dictionary implementation

[davidsteiner]

In preparation for the overhauled message parsing logic, this change refactors the dictionary code by breaking it down into modules and renaming a few things to clarify their purpose to make it easier to add new functionality.

[codecov]

Codecov Report

❌ Patch coverage is 69.05660% with 164 lines in your changes missing coverage. Please review.
✅ Project coverage is 81.88%. Comparing base (452c271) to head (7c8075b).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
crates/hotfix-dictionary/src/layout.rs	28.12%	46 Missing ⚠️
crates/hotfix-dictionary/src/field.rs	50.68%	36 Missing ⚠️
crates/hotfix-dictionary/src/datatype.rs	77.77%	32 Missing ⚠️
crates/hotfix-dictionary/src/component.rs	25.00%	18 Missing ⚠️
crates/hotfix-dictionary/src/dictionary.rs	91.12%	11 Missing ⚠️
crates/hotfix-message/src/parser.rs	0.00%	11 Missing ⚠️
crates/hotfix-dictionary/src/message_definition.rs	57.14%	9 Missing ⚠️
crates/hotfix-dictionary/src/quickfix.rs	97.05%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #222      +/-   ##
==========================================
+ Coverage   81.48%   81.88%   +0.39%     
==========================================
  Files          68       75       +7     
  Lines        6140     6115      -25     
==========================================
+ Hits         5003     5007       +4     
+ Misses       1137     1108      -29     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.