feat: Initial support for DECLARE (cursors)

[ovr]

Hello!

It requires support for arguments, but it's a good initial point for supporting DECLARE.

Thanks

[coveralls]

Pull Request Test Coverage Report for Build 2446379753

• 56 of 59 (94.92%) changed or added relevant lines in 3 files are covered.
• 1 unchanged line in 1 file lost coverage.
• Overall coverage increased (+0.03%) to 89.772%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
src/parser.rs	24	25	96.0%
src/ast/mod.rs	23	25	92.0%

Files with Coverage Reduction	New Missed Lines	%
src/ast/mod.rs	1	78.76%

Totals
Change from base Build 2440505971:	0.03%
Covered Lines:	8698
Relevant Lines:	9689

---

💛 - Coveralls

[alamb]

Thanks @ovr

[alamb]

@ovr thank you -- For some reason github says this PR has a conflict -- can you possibly do so and I'll merge it in?

Thanks again!

[ovr]

@alamb Rebased ✅

[alamb]

Looks great -- thanks again @ovr

[coveralls]

Pull Request Test Coverage Report for Build 2384841888

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

• 53 of 62 (85.48%) changed or added relevant lines in 2 files are covered.
• 3 unchanged lines in 2 files lost coverage.
• Overall coverage increased (+0.03%) to 89.854%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
src/ast/mod.rs	22	26	84.62%
src/parser.rs	31	36	86.11%

Files with Coverage Reduction	New Missed Lines	%
src/parser.rs	1	83.12%
src/ast/mod.rs	2	78.52%

Totals
Change from base Build 2378120823:	0.03%
Covered Lines:	8378
Relevant Lines:	9324

---

💛 - Coveralls