Rename AppCacheResourceTransformer

This change renames AppCacheResourceTransformer to
AppCacheManifestTransfomer, in order to avoid confusion between this
transformer and the CacheResourceTransformer (which caches
transformations done by the chain to save CPU/memory at runtime).

Issue: SPR-11964
Polishing
Add a compiler for SpEL

With these changes an optional compiler is added for SpEL
expressions. The compiler is off by default but can be enabled
via the SpEL parser configuration object or system property
(when SpEL is embedded and parser configuration is not possible).
Not all expressions are currently handled but the common
cases are and it is an extensible compilation framework.

Issue: SPR-10943