[AVRO-3945] Added missing explicit

[mkmkme]

This issue is reported by cppcheck:

impl/json/JsonDom.hh:79:5: style: Class 'Entity' has a constructor with 1 argument that is not explicit. [noExplicitConstructor]
    Entity(Bool v, size_t line = 0) : type_(EntityType::Bool), value_(v), line_(line) {}
    ^
impl/json/JsonDom.hh:82:5: style: Class 'Entity' has a constructor with 1 argument that is not explicit. [noExplicitConstructor]
    Entity(Long v, size_t line = 0) : type_(EntityType::Long), value_(v), line_(line) {}
    ^
impl/json/JsonDom.hh:85:5: style: Class 'Entity' has a constructor with 1 argument that is not explicit. [noExplicitConstructor]
    Entity(Double v, size_t line = 0) : type_(EntityType::Double), value_(v), line_(line) {}
    ^
impl/json/JsonDom.hh:88:5: style: Class 'Entity' has a constructor with 1 argument that is not explicit. [noExplicitConstructor]
    Entity(const std::shared_ptr<String> &v, size_t line = 0) : type_(EntityType::String), value_(v), line_(line) {}
    ^
impl/json/JsonDom.hh:91:5: style: Class 'Entity' has a constructor with 1 argument that is not explicit. [noExplicitConstructor]
    Entity(const std::shared_ptr<Array> &v, size_t line = 0) : type_(EntityType::Arr), value_(v), line_(line) {}
    ^
impl/json/JsonDom.hh:94:5: style: Class 'Entity' has a constructor with 1 argument that is not explicit. [noExplicitConstructor]
    Entity(const std::shared_ptr<Object> &v, size_t line = 0) : type_(EntityType::Obj), value_(v), line_(line) {}
    ^
impl/FileStream.cc:52:5: style: Struct 'FileBufferCopyIn' has a constructor with 1 argument that is not explicit. [noExplicitConstructor]
    FileBufferCopyIn(const char *filename) : h_(::CreateFileA(filename, GENERIC_READ, 0, NULL, OPEN_ALWAYS, FILE_ATTRIBUTE_NORMAL, NULL)) {
    ^
impl/FileStream.cc:235:5: style: Struct 'FileBufferCopyOut' has a constructor with 1 argument that is not explicit. [noExplicitConstructor]
    FileBufferCopyOut(const char *filename) : h_(::CreateFileA(filename, GENERIC_WRITE, 0, NULL, CREATE_ALWAYS, FILE_ATTRIBUTE_NORMAL, NULL)) {
    ^

Verifying this change

This change is a trivial rework / code cleanup without any test coverage.

Documentation

• Does this pull request introduce a new feature? no