feat: add DECLARE parsing for mssql

[devanbenz]

• Adds AST parsing support for DECLARE keyword [MsSql]
• Adds test for multiple variable declaration including a CURSOR and assignment declared scalar variable.

[alamb]

Thanks @devanbenz -- this PR looks good to me other than the CI failure

https://github.com/sqlparser-rs/sqlparser-rs/actions/runs/8888752261/job/24428288785?pr=1235

It looks like a few simple clippy lints to fix

Also thank you @lovasoa for the review

[coveralls]

Pull Request Test Coverage Report for Build 8903948369

Warning: This coverage report may be inaccurate.

This pull request's base commit is no longer the HEAD commit of its target branch. This means it includes changes from outside the original pull request, including, potentially, unrelated coverage changes.

• For more information on this, see Tracking coverage changes with pull request builds.
• To avoid this issue with future PRs, see these Recommended CI Configurations.
• For a quick fix, rebase this PR at GitHub. Your next report should be accurate.

Details

• 81 of 86 (94.19%) changed or added relevant lines in 2 files are covered.
• 1488 unchanged lines in 8 files lost coverage.
• Overall coverage decreased (-0.004%) to 89.192%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
tests/sqlparser_mssql.rs	44	45	97.78%
src/parser/mod.rs	37	41	90.24%

Files with Coverage Reduction	New Missed Lines	%
src/dialect/bigquery.rs	1	75.0%
src/dialect/generic.rs	1	72.0%
src/dialect/mod.rs	16	79.56%
src/ast/query.rs	69	83.9%
tests/sqlparser_bigquery.rs	104	89.45%
src/ast/mod.rs	398	80.41%
src/parser/mod.rs	439	92.82%
tests/sqlparser_common.rs	460	89.57%

Totals
Change from base Build 8896880185:	-0.004%
Covered Lines:	24213
Relevant Lines:	27147

---

💛 - Coveralls

[devanbenz]

Thanks @devanbenz -- this PR looks good to me other than the CI failure

sqlparser-rs/sqlparser-rs/actions/runs/8888752261/job/24428288785?pr=1235

It looks like a few simple clippy lints to fix

Also thank you @lovasoa for the review

Should be good now clippy is not showing any more linting problems. EDIT: disregard, I only ran cargo clippy and it passed but it looks like I need to add other flags 😆

[devanbenz]

@alamb okay cool, sorry about that. Should be good to go now ran all the ci checks locally with cargo.

[alamb]

@alamb okay cool, sorry about that. Should be good to go now ran all the ci checks locally with cargo.

No worries -- thanks @devanbenz for the contribution!