Makes the Ion 1.1 text writer write symbol tokens inline by default, instead of using symbol identifiers.

[tgregg]

Description of changes:
I noticed this when implementing macro-aware transcoding. When transcoding from binary, where symbol IDs are generally available, those symbol IDs were being transcoded to text using symbol identifier syntax, e.g., $1. This was due to an incorrect default in the Ion 1.1 text writer builder.

After this change, transcoded text Ion 1.1 goes from looking like this:

$ion_1_1 (:$ion::set_symbols (:: "foo" "bar")) $1 $2 (:$ion::add_symbols (:: "baz")) $1 $3 (:$ion::set_symbols (:: "abc" "def")) $1 $2 

To this:

$ion_1_1 (:$ion::set_symbols (:: "foo" "bar")) foo bar (:$ion::add_symbols (:: "baz")) foo baz (:$ion::set_symbols (:: "abc" "def")) abc def 

These two streams are data model equivalent, but the latter is easier for humans to read. Anyone who wants to see the symbol identifiers in order to get more information about how the symbols would be encoded in binary can enable this using SymbolInliningStrategy.NEVER_INLINE, as demonstrated by the added unit test.

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[tgregg]

These were unused. The defaults are now contained in the writer builders.