Fix inconsistent enum constant names between schema and serialization

[clementdenis]

• param and resource de/serialization uses Jackson configuration
• schema generation used Enum.name(), should use Jackson instead

Use case: Having custom @JsonProperty("enumValue") on enum constants is useful when implementing an API with param values that are not valid Java identifiers (for example, with dots).

Note: the new method Types.getEnumValuesAndDescriptions might not be at an ideal location, but I could not find a better place to extract it.

[codecov-io]

Codecov Report

Merging #181 into master will increase coverage by 0.03%.
The diff coverage is 100%.

@@ Coverage Diff @@## master #181 +/- ##
============================================
+ Coverage 80.06% 80.09% +0.03% 
Complexity 1715 1715 ============================================
Files 159 159 Lines 5718 5727 +9 Branches 754 753 -1 ============================================
+ Hits 4578 4587 +9 
Misses 856 856 Partials 284 284

Impacted Files	Coverage Δ	Complexity Δ
.../api/server/spi/config/model/SchemaRepository.java	92.42% <100%> (ø)	37 <0> (-2)	⬇️
...e/api/server/spi/discovery/DiscoveryGenerator.java	88.93% <100%> (ø)	62 <0> (-2)	⬇️
...oogle/api/server/spi/swagger/SwaggerGenerator.java	78.08% <100%> (-0.26%)	59 <1> (-1)
.../com/google/api/server/spi/config/model/Types.java	91.93% <100%> (+1.93%)	37 <5> (+5)	⬆️

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[codecov-commenter]

Codecov Report

Merging #181 into master will increase coverage by 0.03%.
The diff coverage is 100.00%.

@@ Coverage Diff @@## master #181 +/- ##
============================================
+ Coverage 80.06% 80.09% +0.03% 
Complexity 1715 1715 ============================================
Files 159 159 Lines 5718 5727 +9 Branches 754 753 -1 ============================================
+ Hits 4578 4587 +9 
Misses 856 856 Partials 284 284 

Impacted Files	Coverage Δ	Complexity Δ
.../api/server/spi/config/model/SchemaRepository.java	92.42% <100.00%> (ø)	37.00 <0.00> (-2.00)
.../com/google/api/server/spi/config/model/Types.java	91.93% <100.00%> (+1.93%)	37.00 <5.00> (+5.00)
...e/api/server/spi/discovery/DiscoveryGenerator.java	88.93% <100.00%> (ø)	62.00 <0.00> (-2.00)
...oogle/api/server/spi/swagger/SwaggerGenerator.java	78.08% <100.00%> (-0.26%)	59.00 <1.00> (-1.00)

---

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Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 39b7374...1a12a04. Read the comment docs.