Fix Import/Export Template for Proto type.

[sagarwaal]

Fixes for Import/Export of PROTO

• Allow import/export of PROTOs/PROTO_ENUMS with SQL keywords in name.

• Allow import/export of columns with nested PROTO types.

  Manually tested export and import of Spanner database with PROTOs and PROTO ENUM.

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 42.95%. Comparing base (817f7ba) to head (dcef9b7).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #1763 +/- ## ========================================= Coverage 42.95% 42.95% Complexity 3390 3390 ========================================= Files 815 815 Lines 47632 47635 +3 Branches 5109 5109 ========================================= + Hits 20460 20463 +3 Misses 25513 25513 Partials 1659 1659 ``` | [Components](https://app.codecov.io/gh/GoogleCloudPlatform/DataflowTemplates/pull/1763/components?src=pr&el=components&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=GoogleCloudPlatform) | Coverage Δ | | |---|---|---| | [spanner-templates](https://app.codecov.io/gh/GoogleCloudPlatform/DataflowTemplates/pull/1763/components?src=pr&el=component&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=GoogleCloudPlatform) | `63.79% <100.00%> (+<0.01%)` | :arrow_up: | | [spanner-import-export](https://app.codecov.io/gh/GoogleCloudPlatform/DataflowTemplates/pull/1763/components?src=pr&el=component&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=GoogleCloudPlatform) | `64.45% <100.00%> (+0.02%)` | :arrow_up: | | [spanner-live-forward-migration](https://app.codecov.io/gh/GoogleCloudPlatform/DataflowTemplates/pull/1763/components?src=pr&el=component&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=GoogleCloudPlatform) | `75.17% <ø> (ø)` | | | [spanner-live-reverse-replication](https://app.codecov.io/gh/GoogleCloudPlatform/DataflowTemplates/pull/1763/components?src=pr&el=component&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=GoogleCloudPlatform) | `71.62% <ø> (ø)` | | | [spanner-bulk-migration](https://app.codecov.io/gh/GoogleCloudPlatform/DataflowTemplates/pull/1763/components?src=pr&el=component&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=GoogleCloudPlatform) | `83.63% <ø> (ø)` | | | [Files](https://app.codecov.io/gh/GoogleCloudPlatform/DataflowTemplates/pull/1763?dropdown=coverage&src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=GoogleCloudPlatform) | Coverage Δ | | |---|---|---| | [...oogle/cloud/teleport/spanner/common/NameUtils.java](https://app.codecov.io/gh/GoogleCloudPlatform/DataflowTemplates/pull/1763?src=pr&el=tree&filepath=v1%2Fsrc%2Fmain%2Fjava%2Fcom%2Fgoogle%2Fcloud%2Fteleport%2Fspanner%2Fcommon%2FNameUtils.java&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=GoogleCloudPlatform#diff-djEvc3JjL21haW4vamF2YS9jb20vZ29vZ2xlL2Nsb3VkL3RlbGVwb3J0L3NwYW5uZXIvY29tbW9uL05hbWVVdGlscy5qYXZh) | `58.62% <ø> (ø)` | | | [...oogle/cloud/teleport/spanner/common/SizedType.java](https://app.codecov.io/gh/GoogleCloudPlatform/DataflowTemplates/pull/1763?src=pr&el=tree&filepath=v1%2Fsrc%2Fmain%2Fjava%2Fcom%2Fgoogle%2Fcloud%2Fteleport%2Fspanner%2Fcommon%2FSizedType.java&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=GoogleCloudPlatform#diff-djEvc3JjL21haW4vamF2YS9jb20vZ29vZ2xlL2Nsb3VkL3RlbGVwb3J0L3NwYW5uZXIvY29tbW9uL1NpemVkVHlwZS5qYXZh) | `91.57% <100.00%> (+0.09%)` | :arrow_up: | | [...ava/com/google/cloud/teleport/spanner/ddl/Ddl.java](https://app.codecov.io/gh/GoogleCloudPlatform/DataflowTemplates/pull/1763?src=pr&el=tree&filepath=v1%2Fsrc%2Fmain%2Fjava%2Fcom%2Fgoogle%2Fcloud%2Fteleport%2Fspanner%2Fddl%2FDdl.java&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=GoogleCloudPlatform#diff-djEvc3JjL21haW4vamF2YS9jb20vZ29vZ2xlL2Nsb3VkL3RlbGVwb3J0L3NwYW5uZXIvZGRsL0RkbC5qYXZh) | `73.33% <100.00%> (+0.07%)` | :arrow_up: | ... and [1 file with indirect coverage changes](https://app.codecov.io/gh/GoogleCloudPlatform/DataflowTemplates/pull/1763/indirect-changes?src=pr&el=tree-more&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=GoogleCloudPlatform)