Deduplicate logtype dictionary entry classes between clp and clp-s.

[gibber9809]

Request

After #1163 is merged clp and clp-s will have very similar logtype dictionary entry implementations with the key differences being:

1. The encoding for logtype entries when written to disk is slightly different (clp explicitly stores every dictionary Id, but clp-s does not)
2. clp-s has support for lazily-initializing info about placeholder locations when decompressing logtype dictionary entries, which helps significantly improve search performance for archives with large array logtype dictionaries

Possible implementation

Possibly we could offer the features needed by both clp and clp-s in one logtype dictionary entry implementation, perhaps by extending the current clp LogtypeDictionaryEntry class.