docs: fix typos in comments, log messages and documentation - #249

Summary

Fixes spelling and grammar typos in doc comments, code comments, documentation and log messages. Every string below was verified against current master before editing.

Doc / code comments:

• Sources/XCRemoteCache/Commands/Postbuild/PostbuildContext.swift: Rrelative to -> Relative to, cache adresses -> cache addresses
• Sources/XCRemoteCache/Commands/Postbuild/PostbuildContext.swift, .../Prebuild/PrebuildContext.swift: targets to downloaded from -> targets to be downloaded from
• Sources/XCRemoteCache/Commands/Plugins/Thinning/ThinningConsumerPostbuildPlugin.swift, .../ArtifactInspector.swift: malformed. Is misses -> malformed. It misses
• Sources/XCRemoteCache/Commands/Plugins/Thinning/ThinningCreatorPlugin.swift: important to enabled that plugin -> important to enable that plugin, that is build as a last step -> that is built as a last step, path of maker file -> path of marker file
• Sources/XCRemoteCache/Dependencies/DependenciesReader.swift: charaters -> characters (x2)
• Sources/xcswift-frontend/XCSwiftcFrontendMain.swift: ramote cache -> remote cache, swift-frontent/xcswift-frontent -> swift-frontend/xcswift-frontend, `swiftc` executaion -> `swiftc` execution, If that is not a case -> If that is not the case
• Rakefile: swift-frontent integration -> swift-frontend integration
• cocoapods-plugin/README.md: A target name that is build at the end -> that is built at the end

Please review carefully -- log message strings changed: Fallbacking to -> Falling back to in 10 places across 7 files (SwiftcOrchestrator.swift, XCCreateUniversalBinary.swift, XCCreateBinary.swift, XCLipoMain.swift, XCLDMain.swift, XCLDPlusPlus.swift, XCSwiftcMain.swift). "Fallbacking" is not an English word, but these are runtime print/defaultLog/errorLog strings rather than comments, so the change is visible in build output. Nothing in Tests/ or e2eTests/ asserts on these strings. All 10 occurrences are changed together so the wording stays consistent across every wrapper tool.

No identifiers were renamed and no logic was changed -- modeMarkerPath, fallbackCommand, lipoCommand and friends are all untouched, and the @param tag in ThinningCreatorPlugin.swift still names the real parameter. 26 insertions / 26 deletions.